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:

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.

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:

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.