In the Linux kernel, the following vulnerability has been resolved:
padata: Put CPU offline callback in ONLINE section to allow failure
syzbot reported the following warning:
DEAD callback error for CPU1
WARNING: kernel/cpu.c:1463 at _cpu_down+0x759/0x1020 kernel/cpu.c:1463, CPU#0: syz.0.1960/14614
at commit 4ae12d8bd9a8 (Merge tag kbuild-fixes-7.0-2 of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux) which tglx traced to padata_cpu_dead() given its the only sub-CPUHP_TEARDOWN_CPU callback that returns an error.
Failure isnt allowed in hotplug states before CPUHP_TEARDOWN_CPU so move the CPU offline callback to the ONLINE section where failure is possible.
References
- https://git.kernel.org/stable/c/3e6c08dd97dcd22a00aee469e0adfa819071d80e
- https://git.kernel.org/stable/c/5a9f29a3e076b637d2234093e57989cf755ded5b
- https://git.kernel.org/stable/c/65dae8b34f0810f3fa9f77c4c63650cd20820693
- https://git.kernel.org/stable/c/9afe53f14a2aae8c4beb30e5ea51641a34f1a3d3
- https://git.kernel.org/stable/c/a6d44f477000c6352de6b05e9e276e62083e5fbf
- https://git.kernel.org/stable/c/c8c4a2972f83c8b68ff03b43cecdb898939ff851