Re: [BUG] powerpc/bpf: Kernel stack corruption in avc_has_perm() during BPF kselftests (test_progs)

On 16/09/26 2:22 pm, Shrikanth Hegde wrote:

Hi Venkat.

Thanks for reporting.

On 9/16/26 2:11 PM, Venkat Rao Bagalkote wrote:

quoted

Hello All!!!


IBM CI has reported a kernel panic on PowerPC (ppc64le, POWER9 
pSeries guest) while running BPF kselftests (test_progs).

What has changed in CI that it is hitting now?

Nothings in specific. Its just that, some of the tests were not run for 
some time, due to build and other issues.

quoted

Environment:

It is very likely same as
https://lore.kernel.org/all/ba9759d0-b1f2-4b33-aff5-769cf89bd584@linux.ibm.com/ (local) 

quoted

Kernel version: 7.3.0-rc3-gf6e7b42bf05b (PREEMPT)
Architecture: ppc64le (POWER9 - IBM,8375-42A pSeries / phyp)
Test Suite: Avocado FVT / kselftests 
(tools/testing/selftests/bpf/test_progs)


Traces:

[ 1359.516833] Kernel panic - not syncing: stack-protector: Kernel 
stack is corrupted in: avc_has_perm+0x23c/0x240
[ 1359.516856] CPU: 0 UID: 0 PID: 49806 Comm: test_progs Tainted: G   
   OE K     7.3.0-rc3-gf6e7b42bf05b #1 PREEMPT
[ 1359.516866] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE, 
[K]=LIVEPATCH
[ 1359.516870] Hardware name: IBM,8375-42A POWER9 (architected) 
0x4e0202 0xf000005 of:IBM,FW950.80 (VL950_131) hv:phyp pSeries
[ 1359.516876] Call Trace:
[ 1359.516880] [c00000011bc67b10] [c0000000014627c0] 
dump_stack_lvl+0x84/0xc0 (unreliable)
[ 1359.516890] [c00000011bc67b40] [c000000000234840] vpanic+0x1b4/0x47c
[ 1359.516897] [c00000011bc67be0] [c000000000234b44] 
do_panic_on_target_cpu+0x0/0x2c
[ 1359.516906] [c00000011bc67c00] [c0000000014f8ce8] 
__stack_chk_fail+0x48/0x60
[ 1359.516913] [c00000011bc67c70] [c00000000092f0bc] 
avc_has_perm+0x23c/0x240
[ 1359.516920] [c00000011bc67d40] [c000000000936fc0] 
selinux_task_getpgid+0x80/0xa0
[ 1359.516927] [c00000011bc67d80] [c000000000920190] 
security_task_getpgid+0x70/0x1c0
[ 1359.516934] [c00000011bc67db0] [c000000000259488] 
do_getpgid+0xa8/0xf0
[ 1359.516941] [c00000011bc67de0] [c0000000002594f0] 
sys_getpgid+0x20/0x30
[ 1359.516948] [c00000011bc67e00] [c000000000034670] 
system_call_exception+0x160/0x480
[ 1359.516957] [c00000011bc67e50] [c00000000000d05c] 
system_call_vectored_common+0x15c/0x2ec


Please let us know if any further debugging or testing with specific 
BPF JIT options is needed.


Regards,

Venkat.