From 80c570537e380c1b8e48754c0ddbce2abcde2d00 Mon Sep 17 00:00:00 2001 From: Jan Kratochvil Date: Thu, 26 Feb 2015 14:08:01 +0100 Subject: SEGV in ppc64_elf_get_synthetic_symtab reading a separate debug file The attached patch fixes the SEGV and lets GDB successfully load all kernel modules installed by default on RHEL 7. Valgrind on F-21 x86_64 host has shown me more clear what is the problem: Reading symbols from /home/jkratoch/t/cordic.ko...Reading symbols from /home/jkratoch/t/cordic.ko.debug...================================================================= ==22763==ERROR: AddressSanitizer: heap-use-after-free on address 0x6120000461c8 at pc 0x150cdbd bp 0x7fffffffc7e0 sp 0x7fffffffc7d0 READ of size 8 at 0x6120000461c8 thread T0 #0 0x150cdbc in ppc64_elf_get_synthetic_symtab /home/jkratoch/redhat/gdb-test-asan/bfd/elf64-ppc.c:3282 #1 0x8c5274 in elf_read_minimal_symbols /home/jkratoch/redhat/gdb-test-asan/gdb/elfread.c:1205 #2 0x8c55e7 in elf_symfile_read /home/jkratoch/redhat/gdb-test-asan/gdb/elfread.c:1268 [...] 0x6120000461c8 is located 264 bytes inside of 288-byte region [0x6120000460c0,0x6120000461e0) freed by thread T0 here: #0 0x7ffff715454f in __interceptor_free (/lib64/libasan.so.1+0x5754f) #1 0xde9cde in xfree common/common-utils.c:98 #2 0x9a04f7 in do_my_cleanups common/cleanups.c:155 #3 0x9a05d3 in do_cleanups common/cleanups.c:177 #4 0x8c538a in elf_read_minimal_symbols /home/jkratoch/redhat/gdb-test-asan/gdb/elfread.c:1229 #5 0x8c55e7 in elf_symfile_read /home/jkratoch/redhat/gdb-test-asan/gdb/elfread.c:1268 [...] previously allocated by thread T0 here: #0 0x7ffff71547c7 in malloc (/lib64/libasan.so.1+0x577c7) #1 0xde9b95 in xmalloc common/common-utils.c:41 #2 0x8c4da2 in elf_read_minimal_symbols /home/jkratoch/redhat/gdb-test-asan/gdb/elfread.c:1147 #3 0x8c55e7 in elf_symfile_read /home/jkratoch/redhat/gdb-test-asan/gdb/elfread.c:1268 [...] SUMMARY: AddressSanitizer: heap-use-after-free /home/jkratoch/redhat/gdb-test-asan/bfd/elf64-ppc.c:3282 ppc64_elf_get_synthetic_symtab [...] ==22763==ABORTING A similar case a few lines later I have fixed in 2010 by: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=3f1eff0a2c7f0e7078f011f55b8e7f710aae0cc2 My testcase does not always reproduce it but at least a bit: * GDB without ppc64 target (even as a secondary one) is reported as "untested" * ASAN-built GDB with ppc64 target always crashes (and PASSes with this fix) * unpatched non-ASAN-built GDB with ppc64 target crashes from commandline * unpatched non-ASAN-built GDB with ppc64 target PASSes from runtest (?) gdb/ChangeLog 2015-02-26 Jan Kratochvil * elfread.c (elf_read_minimal_symbols): Use bfd_alloc for bfd_canonicalize_symtab. gdb/testsuite/ChangeLog 2015-02-26 Jan Kratochvil * gdb.arch/cordic.ko.bz2: New file. * gdb.arch/cordic.ko.debug.bz2: New file. * gdb.arch/ppc64-symtab-cordic.exp: New file. --- gdb/elfread.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'gdb/elfread.c') diff --git a/gdb/elfread.c b/gdb/elfread.c index 65c63f0..4a6576f 100644 --- a/gdb/elfread.c +++ b/gdb/elfread.c @@ -1144,8 +1144,10 @@ elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags, if (storage_needed > 0) { - symbol_table = (asymbol **) xmalloc (storage_needed); - make_cleanup (xfree, symbol_table); + /* Memory gets permanently referenced from ABFD after + bfd_canonicalize_symtab so it must not get freed before ABFD gets. */ + + symbol_table = bfd_alloc (abfd, storage_needed); symcount = bfd_canonicalize_symtab (objfile->obfd, symbol_table); if (symcount < 0) -- cgit v1.1