From 39e4731c78f5d5b1def6c81a2a7bc1417c523480 Mon Sep 17 00:00:00 2001 From: Thomas Preud'homme Date: Thu, 2 Aug 2018 09:07:17 +0000 Subject: [PATCH] [ARM] Fix PR85434: spilling of stack protector guard's address on ARM In case of high register pressure in PIC mode, address of the stack protector's guard can be spilled on ARM targets as shown in PR85434, thus allowing an attacker to control what the canary would be compared against. This is also known as CVE-2018-12886. ARM does lack stack_protect_set and stack_protect_test insn patterns, defining them does not help as the address is expanded regularly and the patterns only deal with the copy and test of the guard with the canary. This problem does not occur for x86 targets because the PIC access and the test can be done in the same instruction. Aarch64 is exempt too because PIC access insn pattern are mov of UNSPEC which prevents it from the second access in the epilogue being CSEd in cse_local pass with the first access in the prologue. The approach followed here is to create new "combined" set and test standard pattern names that take the unexpanded guard and do the set or test. This allows the target to use an opaque pattern (eg. using UNSPEC) to hide the individual instructions being generated to the compiler and split the pattern into generic load, compare and branch instruction after register allocator, therefore avoiding any spilling. This is here implemented for the ARM targets. For targets not implementing these new standard pattern names, the existing stack_protect_set and stack_protect_test pattern names are used. To be able to split PIC access after register allocation, the functions had to be augmented to force a new PIC register load and to control which register it loads into. This is because sharing the PIC register between prologue and epilogue could lead to spilling due to CSE again which an attacker could use to control what the canary gets compared against. 2018-08-02 Thomas Preud'homme gcc/ PR target/85434 * target-insns.def (stack_protect_combined_set): Define new standard pattern name. (stack_protect_combined_test): Likewise. * cfgexpand.c (stack_protect_prologue): Try new stack_protect_combined_set pattern first. * function.c (stack_protect_epilogue): Try new stack_protect_combined_test pattern first. * config/arm/arm.c (require_pic_register): Add pic_reg and compute_now parameters to control which register to use as PIC register and force reloading PIC register respectively. Insert in the stream of insns if possible. (legitimize_pic_address): Expose above new parameters in prototype and adapt recursive calls accordingly. (arm_legitimize_address): Adapt to new legitimize_pic_address prototype. (thumb_legitimize_address): Likewise. (arm_emit_call_insn): Adapt to new require_pic_register prototype. * config/arm/arm-protos.h (legitimize_pic_address): Adapt to prototype change. * config/arm/arm.md (movsi expander): Adapt to legitimize_pic_address prototype change. (stack_protect_combined_set): New insn_and_split pattern. (stack_protect_set): New insn pattern. (stack_protect_combined_test): New insn_and_split pattern. (stack_protect_test): New insn pattern. * config/arm/unspecs.md (UNSPEC_SP_SET): New unspec. (UNSPEC_SP_TEST): Likewise. * doc/md.texi (stack_protect_combined_set): Document new standard pattern name. (stack_protect_set): Clarify that the operand for guard's address is legal. (stack_protect_combined_test): Document new standard pattern name. (stack_protect_test): Clarify that the operand for guard's address is legal. gcc/testsuite/ PR target/85434 * gcc.target/arm/pr85434.c: New test. From-SVN: r263245 --- gcc/ChangeLog | 38 +++++ gcc/cfgexpand.c | 10 ++ gcc/config/arm/arm-protos.h | 2 +- gcc/config/arm/arm.c | 56 +++++-- gcc/config/arm/arm.md | 92 +++++++++++- gcc/config/arm/unspecs.md | 3 + gcc/doc/md.texi | 55 ++++++- gcc/function.c | 37 +++-- gcc/target-insns.def | 2 + gcc/testsuite/ChangeLog | 5 + gcc/testsuite/gcc.target/arm/pr85434.c | 200 +++++++++++++++++++++++++ 11 files changed, 463 insertions(+), 37 deletions(-) create mode 100644 gcc/testsuite/gcc.target/arm/pr85434.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 367a529d4b6..35e4d99751d 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,41 @@ +2018-08-02 Thomas Preud'homme + + PR target/85434 + * target-insns.def (stack_protect_combined_set): Define new standard + pattern name. + (stack_protect_combined_test): Likewise. + * cfgexpand.c (stack_protect_prologue): Try new + stack_protect_combined_set pattern first. + * function.c (stack_protect_epilogue): Try new + stack_protect_combined_test pattern first. + * config/arm/arm.c (require_pic_register): Add pic_reg and compute_now + parameters to control which register to use as PIC register and force + reloading PIC register respectively. Insert in the stream of insns if + possible. + (legitimize_pic_address): Expose above new parameters in prototype and + adapt recursive calls accordingly. + (arm_legitimize_address): Adapt to new legitimize_pic_address + prototype. + (thumb_legitimize_address): Likewise. + (arm_emit_call_insn): Adapt to new require_pic_register prototype. + * config/arm/arm-protos.h (legitimize_pic_address): Adapt to prototype + change. + * config/arm/arm.md (movsi expander): Adapt to legitimize_pic_address + prototype change. + (stack_protect_combined_set): New insn_and_split pattern. + (stack_protect_set): New insn pattern. + (stack_protect_combined_test): New insn_and_split pattern. + (stack_protect_test): New insn pattern. + * config/arm/unspecs.md (UNSPEC_SP_SET): New unspec. + (UNSPEC_SP_TEST): Likewise. + * doc/md.texi (stack_protect_combined_set): Document new standard + pattern name. + (stack_protect_set): Clarify that the operand for guard's address is + legal. + (stack_protect_combined_test): Document new standard pattern name. + (stack_protect_test): Clarify that the operand for guard's address is + legal. + 2018-08-02 David Malcolm * dumpfile.c (dump_user_location_t::dump_user_location_t): Add diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c index 7353d5dce12..0a73ac754cf 100644 --- a/gcc/cfgexpand.c +++ b/gcc/cfgexpand.c @@ -6105,8 +6105,18 @@ stack_protect_prologue (void) { tree guard_decl = targetm.stack_protect_guard (); rtx x, y; + struct expand_operand ops[2]; x = expand_normal (crtl->stack_protect_guard); + create_fixed_operand (&ops[0], x); + create_fixed_operand (&ops[1], DECL_RTL (guard_decl)); + /* Allow the target to compute address of Y and copy it to X without + leaking Y into a register. This combined address + copy pattern allows + the target to prevent spilling of any intermediate results by splitting + it after register allocator. */ + if (maybe_expand_insn (targetm.code_for_stack_protect_combined_set, 2, ops)) + return; + if (guard_decl) y = expand_normal (guard_decl); else diff --git a/gcc/config/arm/arm-protos.h b/gcc/config/arm/arm-protos.h index 8537262ce64..100844e659c 100644 --- a/gcc/config/arm/arm-protos.h +++ b/gcc/config/arm/arm-protos.h @@ -67,7 +67,7 @@ extern int const_ok_for_dimode_op (HOST_WIDE_INT, enum rtx_code); extern int arm_split_constant (RTX_CODE, machine_mode, rtx, HOST_WIDE_INT, rtx, rtx, int); extern int legitimate_pic_operand_p (rtx); -extern rtx legitimize_pic_address (rtx, machine_mode, rtx); +extern rtx legitimize_pic_address (rtx, machine_mode, rtx, rtx, bool); extern rtx legitimize_tls_address (rtx, rtx); extern bool arm_legitimate_address_p (machine_mode, rtx, bool); extern int arm_legitimate_address_outer_p (machine_mode, rtx, RTX_CODE, int); diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c index f5eece4f152..87c728e0eea 100644 --- a/gcc/config/arm/arm.c +++ b/gcc/config/arm/arm.c @@ -7369,20 +7369,26 @@ legitimate_pic_operand_p (rtx x) } /* Record that the current function needs a PIC register. Initialize - cfun->machine->pic_reg if we have not already done so. */ + cfun->machine->pic_reg if we have not already done so. + + A new pseudo register is used for the PIC register if possible, otherwise + PIC_REG must be non NULL and is used instead. COMPUTE_NOW forces the PIC + register to be loaded, irregardless of whether it was loaded previously. */ static void -require_pic_register (void) +require_pic_register (rtx pic_reg, bool compute_now) { /* A lot of the logic here is made obscure by the fact that this routine gets called as part of the rtx cost estimation process. We don't want those calls to affect any assumptions about the real function; and further, we can't call entry_of_function() until we start the real expansion process. */ - if (!crtl->uses_pic_offset_table) + if (!crtl->uses_pic_offset_table || compute_now) { - gcc_assert (can_create_pseudo_p ()); + gcc_assert (can_create_pseudo_p () + || (pic_reg != NULL_RTX && GET_MODE (pic_reg) == Pmode)); if (arm_pic_register != INVALID_REGNUM + && can_create_pseudo_p () && !(TARGET_THUMB1 && arm_pic_register > LAST_LO_REGNUM)) { if (!cfun->machine->pic_reg) @@ -7399,7 +7405,8 @@ require_pic_register (void) rtx_insn *seq, *insn; if (!cfun->machine->pic_reg) - cfun->machine->pic_reg = gen_reg_rtx (Pmode); + cfun->machine->pic_reg = + can_create_pseudo_p () ? gen_reg_rtx (Pmode) : pic_reg; /* Play games to avoid marking the function as needing pic if we are being called as part of the cost-estimation @@ -7410,7 +7417,8 @@ require_pic_register (void) start_sequence (); if (TARGET_THUMB1 && arm_pic_register != INVALID_REGNUM - && arm_pic_register > LAST_LO_REGNUM) + && arm_pic_register > LAST_LO_REGNUM + && can_create_pseudo_p ()) emit_move_insn (cfun->machine->pic_reg, gen_rtx_REG (Pmode, arm_pic_register)); else @@ -7427,15 +7435,29 @@ require_pic_register (void) we can't yet emit instructions directly in the final insn stream. Queue the insns on the entry edge, they will be committed after everything else is expanded. */ - insert_insn_on_edge (seq, - single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))); + if (currently_expanding_to_rtl) + insert_insn_on_edge (seq, + single_succ_edge + (ENTRY_BLOCK_PTR_FOR_FN (cfun))); + else + emit_insn (seq); } } } } +/* Legitimize PIC load to ORIG into REG. If REG is NULL, a new pseudo is + created to hold the result of the load. If not NULL, PIC_REG indicates + which register to use as PIC register, otherwise it is decided by register + allocator. COMPUTE_NOW forces the PIC register to be loaded at the current + location in the instruction stream, irregardless of whether it was loaded + previously. + + Returns the register REG into which the PIC load is performed. */ + rtx -legitimize_pic_address (rtx orig, machine_mode mode, rtx reg) +legitimize_pic_address (rtx orig, machine_mode mode, rtx reg, rtx pic_reg, + bool compute_now) { if (GET_CODE (orig) == SYMBOL_REF || GET_CODE (orig) == LABEL_REF) @@ -7469,7 +7491,7 @@ legitimize_pic_address (rtx orig, machine_mode mode, rtx reg) rtx mem; /* If this function doesn't have a pic register, create one now. */ - require_pic_register (); + require_pic_register (pic_reg, compute_now); pat = gen_calculate_pic_address (reg, cfun->machine->pic_reg, orig); @@ -7520,9 +7542,11 @@ legitimize_pic_address (rtx orig, machine_mode mode, rtx reg) gcc_assert (GET_CODE (XEXP (orig, 0)) == PLUS); - base = legitimize_pic_address (XEXP (XEXP (orig, 0), 0), Pmode, reg); + base = legitimize_pic_address (XEXP (XEXP (orig, 0), 0), Pmode, reg, + pic_reg, compute_now); offset = legitimize_pic_address (XEXP (XEXP (orig, 0), 1), Pmode, - base == reg ? 0 : reg); + base == reg ? 0 : reg, pic_reg, + compute_now); if (CONST_INT_P (offset)) { @@ -8707,7 +8731,8 @@ arm_legitimize_address (rtx x, rtx orig_x, machine_mode mode) { /* We need to find and carefully transform any SYMBOL and LABEL references; so go back to the original address expression. */ - rtx new_x = legitimize_pic_address (orig_x, mode, NULL_RTX); + rtx new_x = legitimize_pic_address (orig_x, mode, NULL_RTX, NULL_RTX, + false /*compute_now*/); if (new_x != orig_x) x = new_x; @@ -8775,7 +8800,8 @@ thumb_legitimize_address (rtx x, rtx orig_x, machine_mode mode) { /* We need to find and carefully transform any SYMBOL and LABEL references; so go back to the original address expression. */ - rtx new_x = legitimize_pic_address (orig_x, mode, NULL_RTX); + rtx new_x = legitimize_pic_address (orig_x, mode, NULL_RTX, NULL_RTX, + false /*compute_now*/); if (new_x != orig_x) x = new_x; @@ -18059,7 +18085,7 @@ arm_emit_call_insn (rtx pat, rtx addr, bool sibcall) ? !targetm.binds_local_p (SYMBOL_REF_DECL (addr)) : !SYMBOL_REF_LOCAL_P (addr))) { - require_pic_register (); + require_pic_register (NULL_RTX, false /*compute_now*/); use_reg (&CALL_INSN_FUNCTION_USAGE (insn), cfun->machine->pic_reg); } diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md index ca2a2f5469f..130531d4eb6 100644 --- a/gcc/config/arm/arm.md +++ b/gcc/config/arm/arm.md @@ -6021,7 +6021,8 @@ operands[1] = legitimize_pic_address (operands[1], SImode, (!can_create_pseudo_p () ? operands[0] - : 0)); + : NULL_RTX), NULL_RTX, + false /*compute_now*/); } " ) @@ -8634,6 +8635,95 @@ (set_attr "conds" "clob")] ) +;; Named patterns for stack smashing protection. +(define_insn_and_split "stack_protect_combined_set" + [(set (match_operand:SI 0 "memory_operand" "=m") + (unspec:SI [(match_operand:SI 1 "memory_operand" "X")] + UNSPEC_SP_SET)) + (match_scratch:SI 2 "=r") + (match_scratch:SI 3 "=r")] + "" + "#" + "reload_completed" + [(parallel [(set (match_dup 0) (unspec:SI [(mem:SI (match_dup 2))] + UNSPEC_SP_SET)) + (clobber (match_dup 2))])] + " +{ + rtx addr = XEXP (operands[1], 0); + if (flag_pic) + { + /* Forces recomputing of GOT base now. */ + operands[1] = legitimize_pic_address (addr, SImode, operands[2], + operands[3], true /*compute_now*/); + } + else + { + if (!address_operand (addr, SImode)) + operands[1] = force_const_mem (SImode, addr); + emit_move_insn (operands[2], operands[1]); + } +}" +) + +(define_insn "stack_protect_set" + [(set (match_operand:SI 0 "memory_operand" "=m") + (unspec:SI [(mem:SI (match_operand:SI 1 "register_operand" "r"))] + UNSPEC_SP_SET)) + (clobber (match_dup 1))] + "" + "ldr\\t%1, [%1]\;str\\t%1, %0\;mov\t%1,0" + [(set_attr "length" "12") + (set_attr "type" "multiple")]) + +(define_insn_and_split "stack_protect_combined_test" + [(set (pc) + (if_then_else + (eq (match_operand:SI 0 "memory_operand" "m") + (unspec:SI [(match_operand:SI 1 "memory_operand" "X")] + UNSPEC_SP_TEST)) + (label_ref (match_operand 2)) + (pc))) + (match_scratch:SI 3 "=r") + (match_scratch:SI 4 "=r")] + "" + "#" + "reload_completed" + [(const_int 0)] +{ + rtx eq, addr; + + addr = XEXP (operands[1], 0); + if (flag_pic) + { + /* Forces recomputing of GOT base now. */ + operands[1] = legitimize_pic_address (addr, SImode, operands[3], + operands[4], + true /*compute_now*/); + } + else + { + if (!address_operand (addr, SImode)) + operands[1] = force_const_mem (SImode, addr); + emit_move_insn (operands[3], operands[1]); + } + emit_insn (gen_stack_protect_test (operands[4], operands[0], operands[3])); + eq = gen_rtx_EQ (VOIDmode, operands[4], const0_rtx); + emit_jump_insn (gen_cbranchsi4 (eq, operands[4], const0_rtx, operands[2])); + DONE; +}) + +(define_insn "stack_protect_test" + [(set (match_operand:SI 0 "register_operand" "=r") + (unspec:SI [(match_operand:SI 1 "memory_operand" "m") + (mem:SI (match_operand:SI 2 "register_operand" "r"))] + UNSPEC_SP_TEST)) + (clobber (match_dup 2))] + "" + "ldr\t%0, [%2]\;ldr\t%2, %1\;eor\t%0, %2, %0" + [(set_attr "length" "12") + (set_attr "type" "multiple")]) + (define_expand "casesi" [(match_operand:SI 0 "s_register_operand" "") ; index to jump on (match_operand:SI 1 "const_int_operand" "") ; lower bound diff --git a/gcc/config/arm/unspecs.md b/gcc/config/arm/unspecs.md index 19416736ef9..8f9dbcb08dc 100644 --- a/gcc/config/arm/unspecs.md +++ b/gcc/config/arm/unspecs.md @@ -86,6 +86,9 @@ UNSPEC_PROBE_STACK ; Probe stack memory reference UNSPEC_NONSECURE_MEM ; Represent non-secure memory in ARMv8-M with ; security extension + UNSPEC_SP_SET ; Represent the setting of stack protector's canary + UNSPEC_SP_TEST ; Represent the testing of stack protector's canary + ; against the guard. ]) (define_c_enum "unspec" [ diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi index 00c1239b786..e7935257783 100644 --- a/gcc/doc/md.texi +++ b/gcc/doc/md.texi @@ -7377,22 +7377,61 @@ builtins. The get/set patterns have a single output/input operand respectively, with @var{mode} intended to be @code{Pmode}. +@cindex @code{stack_protect_combined_set} instruction pattern +@item @samp{stack_protect_combined_set} +This pattern, if defined, moves a @code{ptr_mode} value from an address +whose declaration RTX is given in operand 1 to the memory in operand 0 +without leaving the value in a register afterward. If several +instructions are needed by the target to perform the operation (eg. to +load the address from a GOT entry then load the @code{ptr_mode} value +and finally store it), it is the backend's responsibility to ensure no +intermediate result gets spilled. This is to avoid leaking the value +some place that an attacker might use to rewrite the stack guard slot +after having clobbered it. + +If this pattern is not defined, then the address declaration is +expanded first in the standard way and a @code{stack_protect_set} +pattern is then generated to move the value from that address to the +address in operand 0. + @cindex @code{stack_protect_set} instruction pattern @item @samp{stack_protect_set} -This pattern, if defined, moves a @code{ptr_mode} value from the memory -in operand 1 to the memory in operand 0 without leaving the value in -a register afterward. This is to avoid leaking the value some place -that an attacker might use to rewrite the stack guard slot after -having clobbered it. +This pattern, if defined, moves a @code{ptr_mode} value from the valid +memory location in operand 1 to the memory in operand 0 without leaving +the value in a register afterward. This is to avoid leaking the value +some place that an attacker might use to rewrite the stack guard slot +after having clobbered it. + +Note: on targets where the addressing modes do not allow to load +directly from stack guard address, the address is expanded in a standard +way first which could cause some spills. If this pattern is not defined, then a plain move pattern is generated. +@cindex @code{stack_protect_combined_test} instruction pattern +@item @samp{stack_protect_combined_test} +This pattern, if defined, compares a @code{ptr_mode} value from an +address whose declaration RTX is given in operand 1 with the memory in +operand 0 without leaving the value in a register afterward and +branches to operand 2 if the values were equal. If several +instructions are needed by the target to perform the operation (eg. to +load the address from a GOT entry then load the @code{ptr_mode} value +and finally store it), it is the backend's responsibility to ensure no +intermediate result gets spilled. This is to avoid leaking the value +some place that an attacker might use to rewrite the stack guard slot +after having clobbered it. + +If this pattern is not defined, then the address declaration is +expanded first in the standard way and a @code{stack_protect_test} +pattern is then generated to compare the value from that address to the +value at the memory in operand 0. + @cindex @code{stack_protect_test} instruction pattern @item @samp{stack_protect_test} This pattern, if defined, compares a @code{ptr_mode} value from the -memory in operand 1 with the memory in operand 0 without leaving the -value in a register afterward and branches to operand 2 if the values -were equal. +valid memory location in operand 1 with the memory in operand 0 without +leaving the value in a register afterward and branches to operand 2 if +the values were equal. If this pattern is not defined, then a plain compare pattern and conditional branch pattern is used. diff --git a/gcc/function.c b/gcc/function.c index dee303cdbdd..a95d2f890cd 100644 --- a/gcc/function.c +++ b/gcc/function.c @@ -4893,20 +4893,33 @@ stack_protect_epilogue (void) rtx_code_label *label = gen_label_rtx (); rtx x, y; rtx_insn *seq; + struct expand_operand ops[3]; x = expand_normal (crtl->stack_protect_guard); - if (guard_decl) - y = expand_normal (guard_decl); - else - y = const0_rtx; - - /* Allow the target to compare Y with X without leaking either into - a register. */ - if (targetm.have_stack_protect_test () - && ((seq = targetm.gen_stack_protect_test (x, y, label)) != NULL_RTX)) - emit_insn (seq); - else - emit_cmp_and_jump_insns (x, y, EQ, NULL_RTX, ptr_mode, 1, label); + create_fixed_operand (&ops[0], x); + create_fixed_operand (&ops[1], DECL_RTL (guard_decl)); + create_fixed_operand (&ops[2], label); + /* Allow the target to compute address of Y and compare it with X without + leaking Y into a register. This combined address + compare pattern allows + the target to prevent spilling of any intermediate results by splitting + it after register allocator. */ + if (!maybe_expand_jump_insn (targetm.code_for_stack_protect_combined_test, + 3, ops)) + { + if (guard_decl) + y = expand_normal (guard_decl); + else + y = const0_rtx; + + /* Allow the target to compare Y with X without leaking either into + a register. */ + if (targetm.have_stack_protect_test () + && ((seq = targetm.gen_stack_protect_test (x, y, label)) + != NULL_RTX)) + emit_insn (seq); + else + emit_cmp_and_jump_insns (x, y, EQ, NULL_RTX, ptr_mode, 1, label); + } /* The noreturn predictor has been moved to the tree level. The rtl-level predictors estimate this branch about 20%, which isn't enough to get diff --git a/gcc/target-insns.def b/gcc/target-insns.def index 9a552c3d11c..d39889b3522 100644 --- a/gcc/target-insns.def +++ b/gcc/target-insns.def @@ -96,7 +96,9 @@ DEF_TARGET_INSN (sibcall_value, (rtx x0, rtx x1, rtx opt2, rtx opt3, DEF_TARGET_INSN (simple_return, (void)) DEF_TARGET_INSN (split_stack_prologue, (void)) DEF_TARGET_INSN (split_stack_space_check, (rtx x0, rtx x1)) +DEF_TARGET_INSN (stack_protect_combined_set, (rtx x0, rtx x1)) DEF_TARGET_INSN (stack_protect_set, (rtx x0, rtx x1)) +DEF_TARGET_INSN (stack_protect_combined_test, (rtx x0, rtx x1, rtx x2)) DEF_TARGET_INSN (stack_protect_test, (rtx x0, rtx x1, rtx x2)) DEF_TARGET_INSN (store_multiple, (rtx x0, rtx x1, rtx x2)) DEF_TARGET_INSN (tablejump, (rtx x0, rtx x1)) diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index ac797b302b5..a8da2ab8b24 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2018-08-02 Thomas Preud'homme + + PR target/85434 + * gcc.target/arm/pr85434.c: New test. + 2018-08-01 Martin Sebor PR tree-optimization/86650 diff --git a/gcc/testsuite/gcc.target/arm/pr85434.c b/gcc/testsuite/gcc.target/arm/pr85434.c new file mode 100644 index 00000000000..4143a861f7c --- /dev/null +++ b/gcc/testsuite/gcc.target/arm/pr85434.c @@ -0,0 +1,200 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target fstack_protector }*/ +/* { dg-require-effective-target fpic }*/ +/* { dg-additional-options "-Os -fpic -fstack-protector-strong" } */ + +#include +#include + + +static const unsigned char base64_enc_map[64] = +{ + 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', + 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', + 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', + 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', + 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', + 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', + '8', '9', '+', '/' +}; + +#define BASE64_SIZE_T_MAX ( (size_t) -1 ) /* SIZE_T_MAX is not standard */ + + +void doSmth(void *x); + +#include + + +void check(int n) { + + if (!(n % 2 && n % 3 && n % 5)) { + __asm__ ( "add r8, r8, #1;" ); + } +} + +uint32_t test( + uint32_t a1, + uint32_t a2, + size_t a3, + size_t a4, + size_t a5, + size_t a6) +{ + uint32_t nResult = 0; + uint8_t* h = 0L; + uint8_t X[128]; + uint8_t mac[64]; + size_t len; + + doSmth(&a1); + doSmth(&a2); + doSmth(&a3); + doSmth(&a4); + doSmth(&a5); + doSmth(&a6); + + if (a1 && a2 && a3 && a4 && a5 && a6) { + nResult = 1; + h = (void*)X; + len = sizeof(X); + memset(X, a2, len); + len -= 64; + memcpy(mac ,X, len); + *(h + len) = a6; + + { + + + unsigned char *dst = X; + size_t dlen = a3; + size_t *olen = &a6; + const unsigned char *src = mac; + size_t slen = a4; + size_t i, n; + int C1, C2, C3; + unsigned char *p; + + if( slen == 0 ) + { + *olen = 0; + return( 0 ); + } + + n = slen / 3 + ( slen % 3 != 0 ); + + if( n > ( BASE64_SIZE_T_MAX - 1 ) / 4 ) + { + *olen = BASE64_SIZE_T_MAX; + return( 0 ); + } + + n *= 4; + + if( ( dlen < n + 1 ) || ( NULL == dst ) ) + { + *olen = n + 1; + return( 0 ); + } + + n = ( slen / 3 ) * 3; + + for( i = 0, p = dst; i < n; i += 3 ) + { + C1 = *src++; + C2 = *src++; + C3 = *src++; + + check(i); + + *p++ = base64_enc_map[(C1 >> 2) & 0x3F]; + *p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F]; + *p++ = base64_enc_map[(((C2 & 15) << 2) + (C3 >> 6)) & 0x3F]; + *p++ = base64_enc_map[C3 & 0x3F]; + } + + if( i < slen ) + { + C1 = *src++; + C2 = ( ( i + 1 ) < slen ) ? *src++ : 0; + + *p++ = base64_enc_map[(C1 >> 2) & 0x3F]; + *p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F]; + + if( ( i + 1 ) < slen ) + *p++ = base64_enc_map[((C2 & 15) << 2) & 0x3F]; + else *p++ = '='; + + *p++ = '='; + } + + *olen = p - dst; + *p = 0; + +} + + __asm__ ("mov r8, %0;" : "=r" ( nResult )); + } + else + { + nResult = 2; + } + + doSmth(X); + doSmth(mac); + + + return nResult; +} + +/* The pattern below catches sequences of instructions that were generated + for ARM and Thumb-2 before the fix for this PR. They are of the form: + + ldr rX, + + ldr rY, + ldr rZ, [rX] + + cmp rY, rZ + + bl __stack_chk_fail + + Ideally the optional block would check for the various rX, rY and rZ + registers not being set but this is not possible due to back references + being illegal in lookahead expression in Tcl, thus preventing to use the + only construct that allow to negate a regexp from using the backreferences + to those registers. Instead we go for the heuristic of allowing non ldr/cmp + instructions with the assumptions that (i) those are not part of the stack + protector sequences and (ii) they would only be scheduled here if they don't + conflict with registers used by stack protector. + + Note on the regexp logic: + Allowing non X instructions (where X is ldr or cmp) is done by looking for + some non newline spaces, followed by something which is not X, followed by + an alphanumeric character followed by anything but a newline and ended by a + newline the whole thing an undetermined number of times. The alphanumeric + character is there to force the match of the negative lookahead for X to + only happen after all the initial spaces and thus to check the mnemonic. + This prevents it to match one of the initial space. */ +/* { dg-final { scan-assembler-not {ldr[ \t]+([^,]+), \[(?:sp|fp)[^]]*\](?:\n[ \t]+(?!ldr)\w[^\n]*)*\n[ \t]+ldr[ \t]+([^,]+), \[(?:sp|fp)[^]]*\]\n[ \t]+ldr[ \t]+([^,]+), \[\1\](?:\n[ \t]+(?!ldr)\w[^\n]*)*\n[ \t]+cmp[ \t]+\2, \3(?:\n[ \t]+(?!cmp)\w[^\n]*)*\n[ \t]+bl[ \t]+__stack_chk_fail} } } */ + +/* Likewise for Thumb-1 sequences of instructions prior to the fix for this PR + which had the form: + + ldr rS, + + ldr rT, + + ldr rX, [rS, rT] + + ldr rY, + ldr rZ, [rX] + + cmp rY, rZ + + bl __stack_chk_fail + + Note on the regexp logic: + PC relative offset is checked by looking for a source operand that does not + contain [ or ]. */ +/* { dg-final { scan-assembler-not {ldr[ \t]+([^,]+), \[(?:sp|fp)[^]]*\](?:\n[ \t]+(?!ldr)\w[^\n]*)*\n[ \t]+ldr[ \t]+([^,]+), [^][\n]*(?:\n[ \t]+(?!ldr)\w[^\n]*)*\n[ \t]+ldr[ \t]+([^,]+), \[\1, \2\](?:\n[ \t]+(?!ldr)\w[^\n]*)*\n[ \t]+ldr[ \t]+([^,]+), \[(?:sp|fp)[^]]*\]\n[ \t]+ldr[ \t]+([^,]+), \[\3\](?:\n[ \t]+(?!ldr)\w[^\n]*)*\n[ \t]+cmp[ \t]+\4, \5(?:\n[ \t]+(?!cmp)\w[^\n]*)*\n[ \t]+bl[ \t]+__stack_chk_fail} } } */ -- 2.30.2