diff options
| author | Leon Hwang <leon.hwang@linux.dev> | 2026-09-30 13:36:18 +0800 |
|---|---|---|
| committer | Masami Hiramatsu (Google) <mhiramat@kernel.org> | 2026-10-02 15:51:57 +0900 |
| commit | 7a39c732a22ec4a369af9e19fbe3d666ec83eec4 (patch) | |
| tree | 58fdbe99f1eb36067d3bc2cce87313c46d894a47 /kernel | |
| parent | e0a6249190402a28f1e2925a81acf573157d55ef (diff) | |
kprobes: Skip disarmed probes when checking optkprobe overlap
On x86, an optkprobe at A replaces five bytes with a jump. If a disabled
probe B is at A+2, get_optimized_kprobe() stops at B when arming a new
probe C at A+4. It leaves A optimized:
A A+1 A+2 A+3 A+4
A's jump | e9 | d0 | d1 | d2 | d3 |
after C | e9 | d0 | d1 | d2 | cc |
The INT3 for C overwrites the last byte of A's jump displacement, so
execution can jump to the wrong address. B can have prepared optinsns
while disarmed, but has no jump to unoptimize.
Continue past disarmed and unprepared probes to find the active optimized
probe before arming a probe in its jump.
Link: https://lore.kernel.org/all/20260930053618.104498-1-leon.hwang@linux.dev/
Fixes: afd66255b9a4 ("kprobes: Introduce kprobes jump optimization")
Cc: stable@vger.kernel.org
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/kprobes.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 4edd8ca5c657..e787e4948c8b 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -496,14 +496,16 @@ static bool kprobe_queued(struct kprobe *p) static struct kprobe *get_optimized_kprobe(kprobe_opcode_t *addr) { int i; - struct kprobe *p = NULL; + struct kprobe *p; struct optimized_kprobe *op; /* Don't check i == 0, since that is a breakpoint case. */ - for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH / sizeof(kprobe_opcode_t); i++) + for (i = 1; i < MAX_OPTIMIZED_LENGTH / sizeof(kprobe_opcode_t); i++) { p = get_kprobe(addr - i); + /* A disabled probe can have prepared, but inactive, optinsns. */ + if (!p || !kprobe_optready(p) || kprobe_disarmed(p)) + continue; - if (p && kprobe_optready(p)) { op = container_of(p, struct optimized_kprobe, kp); if (arch_within_optimized_kprobe(op, addr)) return p; |