kprobes: Skip disarmed probes when checking optkprobe overlap

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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: afd66255b9 ("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>

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Leon Hwang 2026-09-30 13:36:18 +08:00 • committed by Masami Hiramatsu (Google)

parent e0a6249190

commit 7a39c732a2

1 changed files with 5 additions and 3 deletions

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kernel/kprobes.c

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