Tom de Vries 72535eb14b [gdb/tui] Fix segfault in tui_find_disassembly_address ... PR29040 describes a FAIL for test-case gdb.threads/next-fork-other-thread.exp and target board unix/-m32. The FAIL happens due to the test executable running into an assert, which is caused by a forked child segfaulting, like so: ... Program terminated with signal SIGSEGV, Segmentation fault. #0 0x00000000 in ?? () ... I tried to reproduce the segfault with exec next-fork-other-thread-fork, using TUI layout asm. I set a breakpoint at fork and ran to the breakpoint, and somewhere during the following session I ran into a gdb segfault here in tui_find_disassembly_address: ... /* Disassemble forward. */ next_addr = tui_disassemble (gdbarch, asm_lines, new_low, max_lines); last_addr = asm_lines.back ().addr; ... due to asm_lines being empty after the call to tui_disassemble, while asm_lines.back () assumes that it's not empty. I have not been able to reproduce that segfault in that original setting, I'm not sure of the exact scenario (though looking back it probably involved "set detach-on-fork off"). What likely happened is that I managed to reproduce PR29040, and TUI (attempted to) display the disassembly for address 0, which led to the gdb segfault. When gdb_print_insn encounters an insn it cannot print because it can't read the memory, it throws a MEMORY_ERROR that is caught by tui_disassemble. The specific bit that causes the gdb segfault is that if gdb_print_insn throws a MEMORY_ERROR for the first insn in tui_disassemble, it returns an empty asm_lines. FWIW, I did manage to reproduce the gdb segfault as follows: ... $ gdb -q \ -iex "set pagination off" \ /usr/bin/rustc \ -ex "set breakpoint pending on" \ -ex "b dl_main" \ -ex run \ -ex "up 4" \ -ex "layout asm" \ -ex "print \$pc" ... <TUI> ... $1 = (void (*)()) 0x1 (gdb) ... Now press <up>, and the segfault triggers. Fix the segfault by handling asm_lines.empty () results of tui_disassemble in tui_find_disassembly_address. I've written a unit test that exercises this scenario. Tested on x86_64-linux. Reviewed-by: Kevin Buettner <kevinb@redhat.com> PR tui/30823 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30823		2023-09-28 20:17:33 +02:00
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ChangeLog-1998-2003
tui-command.c
tui-command.h
tui-data.c
tui-data.h
tui-disasm.c	[gdb/tui] Fix segfault in tui_find_disassembly_address	2023-09-28 20:17:33 +02:00
tui-disasm.h
tui-file.c
tui-file.h
tui-hooks.c
tui-hooks.h
tui-interp.c
tui-io.c
tui-io.h
tui-layout.c
tui-layout.h
tui-location.c
tui-location.h
tui-out.c
tui-out.h
tui-regs.c
tui-regs.h
tui-source.c
tui-source.h
tui-stack.c
tui-stack.h
tui-win.c
tui-win.h
tui-wingeneral.c
tui-wingeneral.h
tui-winsource.c
tui-winsource.h
tui.c
tui.h