From e8f8842d90abe5eafa8c32f08fbc3a747a45747c Mon Sep 17 00:00:00 2001 From: Tamar Christina Date: Tue, 24 Sep 2019 14:46:17 +0100 Subject: [PATCH] Arm: Fix out of range conditional branch (PR/24991) The fix for PR12848 introduced an off by one error in the mask, this corrected the negative overflows but not the positive overflows. As a result the conditional branch instructions accepted a too wide positive immediate which resulted in it corrupting the instruction during encoding. The relocation I believe has been incorrectly named, to be consistent with the other relocations it should have been named BRANCH21 which is why the masks for it are confusing. I've replaced the masks with a function out_of_range_p which should make it harder to make such mistakes. The mask for BL/BLX on Armv6t+ is also wrong, the extended range is 25-bits and so the mask should be checking for 24-bits for positive overflow. gas/ChangeLog: PR gas/24991 * config/tc-arm.c (out_of_range_p): New. (md_apply_fix): Use it in BFD_RELOC_THUMB_PCREL_BRANCH9, BFD_RELOC_THUMB_PCREL_BRANCH12, BFD_RELOC_THUMB_PCREL_BRANCH20, BFD_RELOC_THUMB_PCREL_BRANCH23, BFD_RELOC_THUMB_PCREL_BRANCH25 * testsuite/gas/arm/pr24991.d: New test. * testsuite/gas/arm/pr24991.l: New test. * testsuite/gas/arm/pr24991.s: New test. --- gas/ChangeLog | 11 +++++++++++ gas/config/tc-arm.c | 23 ++++++++++++++++------- gas/testsuite/gas/arm/pr24991.d | 4 ++++ gas/testsuite/gas/arm/pr24991.l | 2 ++ gas/testsuite/gas/arm/pr24991.s | 5 +++++ 5 files changed, 38 insertions(+), 7 deletions(-) create mode 100644 gas/testsuite/gas/arm/pr24991.d create mode 100644 gas/testsuite/gas/arm/pr24991.l create mode 100644 gas/testsuite/gas/arm/pr24991.s diff --git a/gas/ChangeLog b/gas/ChangeLog index 764789bca0d..41fc4cefd8a 100644 --- a/gas/ChangeLog +++ b/gas/ChangeLog @@ -1,3 +1,14 @@ +2019-09-24 Tamar Christina + + PR gas/24991 + * config/tc-arm.c (out_of_range_p): New. + (md_apply_fix): Use it in BFD_RELOC_THUMB_PCREL_BRANCH9, + BFD_RELOC_THUMB_PCREL_BRANCH12, BFD_RELOC_THUMB_PCREL_BRANCH20, + BFD_RELOC_THUMB_PCREL_BRANCH23, BFD_RELOC_THUMB_PCREL_BRANCH25 + * testsuite/gas/arm/pr24991.d: New test. + * testsuite/gas/arm/pr24991.l: New test. + * testsuite/gas/arm/pr24991.s: New test. + 2019-09-23 Alan Modra * config/obj-ecoff.c: Include ecoff-bfd.h. diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c index 2f394bae505..1f462307ed9 100644 --- a/gas/config/tc-arm.c +++ b/gas/config/tc-arm.c @@ -107,6 +107,15 @@ enum arm_float_abi should define CPU_DEFAULT here. */ #endif +/* Perform range checks on positive and negative overflows by checking if the + VALUE given fits within the range of an BITS sized immediate. */ +static bfd_boolean out_of_range_p (offsetT value, offsetT bits) + { + gas_assert (bits < (offsetT)(sizeof (value) * 8)); + return (value & ~((1 << bits)-1)) + && ((value & ~((1 << bits)-1)) != ~((1 << bits)-1)); +} + #ifndef FPU_DEFAULT # ifdef TE_LINUX # define FPU_DEFAULT FPU_ARCH_FPA @@ -28089,7 +28098,7 @@ md_apply_fix (fixS * fixP, break; case BFD_RELOC_THUMB_PCREL_BRANCH9: /* Conditional branch. */ - if ((value & ~0xff) && ((value & ~0xff) != ~0xff)) + if (out_of_range_p (value, 8)) as_bad_where (fixP->fx_file, fixP->fx_line, BAD_RANGE); if (fixP->fx_done || !seg->use_rela_p) @@ -28101,7 +28110,7 @@ md_apply_fix (fixS * fixP, break; case BFD_RELOC_THUMB_PCREL_BRANCH12: /* Unconditional branch. */ - if ((value & ~0x7ff) && ((value & ~0x7ff) != ~0x7ff)) + if (out_of_range_p (value, 11)) as_bad_where (fixP->fx_file, fixP->fx_line, BAD_RANGE); if (fixP->fx_done || !seg->use_rela_p) @@ -28112,6 +28121,7 @@ md_apply_fix (fixS * fixP, } break; + /* This relocation is misnamed, it should be BRANCH21. */ case BFD_RELOC_THUMB_PCREL_BRANCH20: if (fixP->fx_addsy && (S_GET_SEGMENT (fixP->fx_addsy) == seg) @@ -28122,7 +28132,7 @@ md_apply_fix (fixS * fixP, /* Force a relocation for a branch 20 bits wide. */ fixP->fx_done = 0; } - if ((value & ~0x1fffff) && ((value & ~0x0fffff) != ~0x0fffff)) + if (out_of_range_p (value, 20)) as_bad_where (fixP->fx_file, fixP->fx_line, _("conditional branch out of range")); @@ -28201,12 +28211,11 @@ md_apply_fix (fixS * fixP, fixP->fx_r_type = BFD_RELOC_THUMB_PCREL_BRANCH23; #endif - if ((value & ~0x3fffff) && ((value & ~0x3fffff) != ~0x3fffff)) + if (out_of_range_p (value, 22)) { if (!(ARM_CPU_HAS_FEATURE (cpu_variant, arm_ext_v6t2))) as_bad_where (fixP->fx_file, fixP->fx_line, BAD_RANGE); - else if ((value & ~0x1ffffff) - && ((value & ~0x1ffffff) != ~0x1ffffff)) + else if (out_of_range_p (value, 24)) as_bad_where (fixP->fx_file, fixP->fx_line, _("Thumb2 branch out of range")); } @@ -28217,7 +28226,7 @@ md_apply_fix (fixS * fixP, break; case BFD_RELOC_THUMB_PCREL_BRANCH25: - if ((value & ~0x0ffffff) && ((value & ~0x0ffffff) != ~0x0ffffff)) + if (out_of_range_p (value, 24)) as_bad_where (fixP->fx_file, fixP->fx_line, BAD_RANGE); if (fixP->fx_done || !seg->use_rela_p) diff --git a/gas/testsuite/gas/arm/pr24991.d b/gas/testsuite/gas/arm/pr24991.d new file mode 100644 index 00000000000..2acca2d656c --- /dev/null +++ b/gas/testsuite/gas/arm/pr24991.d @@ -0,0 +1,4 @@ +#as: -march=armv7-a +#source: pr24991.s +#error_output: pr24991.l + diff --git a/gas/testsuite/gas/arm/pr24991.l b/gas/testsuite/gas/arm/pr24991.l new file mode 100644 index 00000000000..4fc58751c8d --- /dev/null +++ b/gas/testsuite/gas/arm/pr24991.l @@ -0,0 +1,2 @@ +[^:]*: Assembler messages: +[^:]*:4: Error: conditional branch out of range diff --git a/gas/testsuite/gas/arm/pr24991.s b/gas/testsuite/gas/arm/pr24991.s new file mode 100644 index 00000000000..27f8daff1c8 --- /dev/null +++ b/gas/testsuite/gas/arm/pr24991.s @@ -0,0 +1,5 @@ + .arch armv7-a + .syntax unified + .thumb + beq .+ 0x124f80 + -- 2.30.2