On arm-linux the linaro CI occasionally reports:
...
(gdb) up 10
#4 0x0001b864 in pthread_join ()
(gdb) FAIL: gdb.threads/staticthreads.exp: up 10
...
while this is expected:
...
(gdb) up 10
#3 0x00010568 in main (argc=1, argv=0xfffeede4) at staticthreads.c:76
76 pthread_join (thread, NULL);
(gdb) PASS: gdb.threads/staticthreads.exp: up 10
...
Thiago investigated the problem, and using valgrind found an invalid read in
arm_exidx_fill_cache.
The problem happens as follows:
- an objfile and corresponding per_bfd are allocated
- some memory is allocated in arm_exidx_new_objfile using
objfile->objfile_obstack, for the "exception table entry cache".
- a symbol reread is triggered, and the objfile, including the
objfile_obstack, is destroyed
- a new objfile is allocated, using the same per_bfd
- again arm_exidx_new_objfile is called, but since the same per_bfd is used,
it doesn't allocate any new memory for the "exception table entry cache".
- the "exception table entry cache" is accessed by arm_exidx_fill_cache,
and we have a use-after-free.
This is a regression since commit a2726d4ff8 ("[ARM] Store exception handling
information per-bfd instead of per-objfile"), which changed the "exception
table entry cache" from per-objfile to per-bfd, but failed to update the
obstack_alloc.
Fix this by using objfile->per_bfd->storage_obstack instead of
objfile->objfile_obstack.
I couldn't reproduce the FAIL myself, but Thiago confirmed that the patch
fixes it.
Tested on arm-linux.
Approved-By: Luis Machado <luis.machado@arm.com>
PR tdep/31254
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31254
When a user attempts to use the "list ." command with an inferior that
doesn't have debug symbols, GDB would crash. This was reported as PR
gdb/31256.
The crash would happen when attempting to get the current symtab_and_line
for the stop location, because the symtab would return a null pointer
and we'd attempt to dereference it to print the line.
This commit fixes that by checking for an empty symtab and erroring out
of the function if it happens.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31256
Approved-By: Tom Tromey <tom@tromey.com>
