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| author | Nadav Amit <namit@vmware.com> | 2023-02-08 07:17:08 +0000 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2023-02-08 12:03:27 -0800 |
| commit | ae052e3ae09572194d7e574906db7272041577d3 (patch) | |
| tree | adb6f9271a31518e91964af558284e9f0079fc57 /arch | |
| parent | 9d2c7203ffdb846399b82b0660563c89e918c751 (diff) | |
| download | lwn-ae052e3ae09572194d7e574906db7272041577d3.tar.gz lwn-ae052e3ae09572194d7e574906db7272041577d3.zip | |
x86/kprobes: Fix 1 byte conditional jump target
Commit 3bc753c06dd0 ("kbuild: treat char as always unsigned") broke
kprobes. Setting a probe-point on 1 byte conditional jump can cause the
kernel to crash when the (signed) relative jump offset gets treated as
unsigned.
Fix by replacing the unsigned 'immediate.bytes' (plus a cast) with the
signed 'immediate.value' when assigning to the relative jump offset.
[ dhansen: clarified changelog ]
Fixes: 3bc753c06dd0 ("kbuild: treat char as always unsigned")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230208071708.4048-1-namit%40vmware.com
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index b36f3c367cb2..695873c0f50b 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -625,7 +625,7 @@ static int prepare_emulation(struct kprobe *p, struct insn *insn) /* 1 byte conditional jump */ p->ainsn.emulate_op = kprobe_emulate_jcc; p->ainsn.jcc.type = opcode & 0xf; - p->ainsn.rel32 = *(char *)insn->immediate.bytes; + p->ainsn.rel32 = insn->immediate.value; break; case 0x0f: opcode = insn->opcode.bytes[1]; |