In the Linux kernel, the following vulnerability has been resolved:
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:
<pre>
A A+1 A+2 A+3 A+4
</pre>
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.