diff options
| author | Ingo Molnar <mingo@kernel.org> | 2025-12-01 10:42:27 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-12-01 10:42:27 +0100 |
| commit | 6ec33db1aaf06a76fb063610e668f8e12f32ebbf (patch) | |
| tree | 0aaf477b1e67a97bde3171664ded5bc2c3d8cbdf | |
| parent | 59bfa6408214b6533d8691715cf5459e89b45b89 (diff) | |
objtool: Fix segfault on unknown alternatives
So 'objtool --link -d vmlinux.o' gets surprised by this endbr64+endbr64 pattern
in ___bpf_prog_run():
___bpf_prog_run:
1e7680: ___bpf_prog_run+0x0 push %r12
1e7682: ___bpf_prog_run+0x2 mov %rdi,%r12
1e7685: ___bpf_prog_run+0x5 push %rbp
1e7686: ___bpf_prog_run+0x6 xor %ebp,%ebp
1e7688: ___bpf_prog_run+0x8 push %rbx
1e7689: ___bpf_prog_run+0x9 mov %rsi,%rbx
1e768c: ___bpf_prog_run+0xc movzbl (%rbx),%esi
1e768f: ___bpf_prog_run+0xf movzbl %sil,%edx
1e7693: ___bpf_prog_run+0x13 mov %esi,%eax
1e7695: ___bpf_prog_run+0x15 mov 0x0(,%rdx,8),%rdx
1e769d: ___bpf_prog_run+0x1d jmp 0x1e76a2 <__x86_indirect_thunk_rdx>
1e76a2: ___bpf_prog_run+0x22 endbr64
1e76a6: ___bpf_prog_run+0x26 endbr64
1e76aa: ___bpf_prog_run+0x2a mov 0x4(%rbx),%edx
And crashes due to blindly dereferencing alt->insn->alt_group.
Bail out on NULL ->alt_group, which produces this warning and continues
with the disassembly, instead of a segfault:
.git/O/vmlinux.o: warning: objtool: <alternative.1e769d>: failed to disassemble alternative
Cc: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | tools/objtool/disas.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/tools/objtool/disas.c b/tools/objtool/disas.c index 441b9306eafc..2b5059f55e40 100644 --- a/tools/objtool/disas.c +++ b/tools/objtool/disas.c @@ -684,6 +684,9 @@ char *disas_alt_name(struct alternative *alt) * '?' unknown flag */ + if (!alt->insn->alt_group) + return NULL; + feature = alt->insn->alt_group->feature; num = alt_feature(feature); flags = alt_flags(feature); |