From 830b67068cebe7db0eb0db3fa19244e03859fae0 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Fri, 12 Jul 2019 09:53:02 +0200 Subject: [PATCH] [readline] Fix heap-buffer-overflow in update_line When: - building trunk gdb with '-fsanitize=address -lasan', - running gdb tests with "export ASAN_OPTIONS=detect_leaks=0", I run into a heap-buffer-overflow failure for gdb.base/utf8-identifiers.exp. In more detail, the libasan error report looks like this: ... ================================================================= ==22340==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x619000054a80 at pc 0x7fcd0306b4c9 bp 0x7fffb1a8d880 sp 0x7fffb1a8d030 READ of size 32766 at 0x619000054a80 thread T0 #0 0x7fcd0306b4c8 (/usr/lib64/libasan.so.4+0xae4c8) #1 0x15f12a1 in update_line /data/gdb_versions/devel/src/readline/display.c:1377 #2 0x15f03cb in rl_redisplay /data/gdb_versions/devel/src/readline/display.c:1204 #3 0x15bf932 in readline_internal_setup /data/gdb_versions/devel/src/readline/readline.c:394 #4 0x15fe723 in _rl_callback_newline /data/gdb_versions/devel/src/readline/callback.c:89 #5 0x15fe7ef in rl_callback_handler_install /data/gdb_versions/devel/src/readline/callback.c:102 #6 0xd7bce6 in gdb_rl_callback_handler_install(char const*) /data/gdb_versions/devel/src/gdb/event-top.c:319 #7 0xd7c0c6 in display_gdb_prompt(char const*) /data/gdb_versions/devel/src/gdb/event-top.c:409 #8 0xd7d6c1 in command_line_handler(std::unique_ptr >&&) /data/gdb_versions/devel/src/gdb/event-top.c:776 #9 0xd7b92a in gdb_rl_callback_handler /data/gdb_versions/devel/src/gdb/event-top.c:217 #10 0x15ff479 in rl_callback_read_char /data/gdb_versions/devel/src/readline/callback.c:220 #11 0xd7b4d5 in gdb_rl_callback_read_char_wrapper_noexcept /data/gdb_versions/devel/src/gdb/event-top.c:175 #12 0xd7b6b5 in gdb_rl_callback_read_char_wrapper /data/gdb_versions/devel/src/gdb/event-top.c:192 #13 0xd7c8aa in stdin_event_handler(int, void*) /data/gdb_versions/devel/src/gdb/event-top.c:514 #14 0xd76ca7 in handle_file_event /data/gdb_versions/devel/src/gdb/event-loop.c:731 #15 0xd7751f in gdb_wait_for_event /data/gdb_versions/devel/src/gdb/event-loop.c:857 #16 0xd7547e in gdb_do_one_event() /data/gdb_versions/devel/src/gdb/event-loop.c:321 #17 0xd75526 in start_event_loop() /data/gdb_versions/devel/src/gdb/event-loop.c:370 #18 0x101b04c in captured_command_loop /data/gdb_versions/devel/src/gdb/main.c:331 #19 0x101de73 in captured_main /data/gdb_versions/devel/src/gdb/main.c:1173 #20 0x101df03 in gdb_main(captured_main_args*) /data/gdb_versions/devel/src/gdb/main.c:1188 #21 0x872dba in main /data/gdb_versions/devel/src/gdb/gdb.c:32 #22 0x7fcd00f2ff49 in __libc_start_main (/lib64/libc.so.6+0x20f49) #23 0x872bc9 in _start (/data/gdb_versions/devel/build/gdb/gdb+0x872bc9) 0x619000054a80 is located 0 bytes to the right of 1024-byte region [0x619000054680,0x619000054a80) allocated by thread T0 here: #0 0x7fcd03099510 in malloc (/usr/lib64/libasan.so.4+0xdc510) #1 0xae0078 in xmalloc /data/gdb_versions/devel/src/gdb/common/common-utils.c:44 #2 0x15eaccb in init_line_structures /data/gdb_versions/devel/src/readline/display.c:458 #3 0x15eb4d8 in rl_redisplay /data/gdb_versions/devel/src/readline/display.c:526 #4 0x15bf932 in readline_internal_setup /data/gdb_versions/devel/src/readline/readline.c:394 #5 0x15fe723 in _rl_callback_newline /data/gdb_versions/devel/src/readline/callback.c:89 #6 0x15fe7ef in rl_callback_handler_install /data/gdb_versions/devel/src/readline/callback.c:102 #7 0xd7bce6 in gdb_rl_callback_handler_install(char const*) /data/gdb_versions/devel/src/gdb/event-top.c:319 #8 0xd7c0c6 in display_gdb_prompt(char const*) /data/gdb_versions/devel/src/gdb/event-top.c:409 #9 0xaa041b in cli_interp_base::pre_command_loop() /data/gdb_versions/devel/src/gdb/cli/cli-interp.c:286 #10 0xf5342a in interp_pre_command_loop(interp*) /data/gdb_versions/devel/src/gdb/interps.c:320 #11 0x101b047 in captured_command_loop /data/gdb_versions/devel/src/gdb/main.c:328 #12 0x101de73 in captured_main /data/gdb_versions/devel/src/gdb/main.c:1173 #13 0x101df03 in gdb_main(captured_main_args*) /data/gdb_versions/devel/src/gdb/main.c:1188 #14 0x872dba in main /data/gdb_versions/devel/src/gdb/gdb.c:32 #15 0x7fcd00f2ff49 in __libc_start_main (/lib64/libc.so.6+0x20f49) SUMMARY: AddressSanitizer: heap-buffer-overflow (/usr/lib64/libasan.so.4+0xae4c8) Shadow bytes around the buggy address: 0x0c3280002900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c3280002910: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c3280002920: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c3280002930: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c3280002940: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 =>0x0c3280002950:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c3280002960: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c3280002970: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c3280002980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c3280002990: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c32800029a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Shadow byte legend (one shadow byte represents 8 application bytes): Addressable: 00 Partially addressable: 01 02 03 04 05 06 07 Heap left redzone: fa Freed heap region: fd Stack left redzone: f1 Stack mid redzone: f2 Stack right redzone: f3 Stack after return: f5 Stack use after scope: f8 Global redzone: f9 Global init order: f6 Poisoned by user: f7 Container overflow: fc Array cookie: ac Intra object redzone: bb ASan internal: fe Left alloca redzone: ca Right alloca redzone: cb ==22340==ABORTING ... I've written an assert in rl_redisplay that formulates the error condition: ... @@ -1387,6 +1389,10 @@ rl_redisplay (void) cpos_adjusted = 0; + assert (last_lmargin + (_rl_screenwidth + visible_wrap_offset) + <= line_size); + assert (lmargin + (_rl_screenwidth + (lmargin ? 0 : wrap_offset)) + <= line_size); update_line (&visible_line[last_lmargin], &invisible_line[lmargin], 0, _rl_screenwidth + visible_wrap_offset, _rl_screenwidth + (lmargin ? 0 : wrap_offset), 0); ... which triggers without needing the address sanitizer (or even an executable), like this: ... $ TERM=dumb gdb -q -ex "set width 0" gdb: src/display.c:1393: rl_redisplay: Assertion `last_lmargin + (_rl_screenwidth + visible_wrap_offset) <= line_size' failed. Aborted (core dumped) ... The basic problem is this: visible_line and invisible_line have length line_size, but the update_line call assumes that line_size is at least _rl_screenwidth + 1. Executing "set width 0" sets _rl_screenwidth to 32766 but doesn't affect line_size, which is initialized to 1024. Fix this by ensuring in init_line_structures and rl_redisplay that line_size is at least _rl_screenwidth + 1. Tested on x86_64-linux. Reviewed by readline maintainer ( https://sourceware.org/ml/gdb-patches/2019-05/msg00566.html ). readline/ChangeLog.gdb: 2019-07-12 Tom de Vries Chet Ramey PR cli/24514 * readline/display.c (init_line_structures, rl_redisplay): Ensure line_size is at least _rl_screenwidth + 1. --- readline/ChangeLog.gdb | 7 +++++++ readline/display.c | 5 +++++ 2 files changed, 12 insertions(+) diff --git a/readline/ChangeLog.gdb b/readline/ChangeLog.gdb index c59329ee7d2..e71ee96b36e 100644 --- a/readline/ChangeLog.gdb +++ b/readline/ChangeLog.gdb @@ -1,3 +1,10 @@ +2019-07-12 Tom de Vries + Chet Ramey + + PR cli/24514 + * readline/display.c (init_line_structures, rl_redisplay): Ensure + line_size is at least _rl_screenwidth + 1. + 2019-01-31 Alan Hayward * config.h.in: Add SOURCE/EXTENSION macros. diff --git a/readline/display.c b/readline/display.c index 90443057974..842adf5067f 100644 --- a/readline/display.c +++ b/readline/display.c @@ -450,6 +450,9 @@ init_line_structures (minsize) { register int n; + if (minsize <= _rl_screenwidth) /* XXX - for gdb */ + minsize = _rl_screenwidth + 1; + if (invisible_line == 0) /* initialize it */ { if (line_size < minsize) @@ -526,6 +529,8 @@ rl_redisplay () init_line_structures (0); rl_on_new_line (); } + else if (line_size <= _rl_screenwidth) + init_line_structures (_rl_screenwidth + 1); /* Draw the line into the buffer. */ cpos_buffer_position = -1; -- 2.30.2