CVE-2024-56665

In the Linux kernel, the following vulnerability has been resolved:

bpf,perf: Fix invalid progarray access in perfeventdetachbpf_prog

Syzbot reported [1] crash that happens for following tracing scenario:

• create tracepoint perf event with attr.inherit=1, attach it to the process and set bpf program to it

• attached process forks -> chid creates inherited event

  the new child event shares the parent's bpf program and tpevent (hence progarray) which is global for tracepoint

• exit both process and its child -> release both events

• first perfeventdetachbpfprog call will release tpevent->progarray and second perfeventdetachbpfprog will crash, because tpevent->progarray is NULL

The fix makes sure the perfeventdetachbpfprog checks prog_array is valid before it tries to remove the bpf program from it.

[1] https://lore.kernel.org/bpf/Z1MR6dCIKajNS6nU@krava/T/#m91dbf0688221ec7a7fc95e896a7ef9ff93b0b8ad