diff options
| author | Viktor Malik <vmalik@redhat.com> | 2026-03-09 15:40:45 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-03-19 16:08:31 +0100 |
| commit | 98074e16742ae87fb82e234b419783c5ffc9baea (patch) | |
| tree | e606a528d949b7da7d7285abe03d34015f4594ed /arch/powerpc/perf/callchain.c | |
| parent | 9e84113ea6ec22775a3bd8dbfae471906233f5da (diff) | |
powerpc, perf: Check that current->mm is alive before getting user callchain
[ Upstream commit e9bbfb4bfa86c6b5515b868d6982ac60505d7e39 ]
It may happen that mm is already released, which leads to kernel panic.
This adds the NULL check for current->mm, similarly to
commit 20afc60f892d ("x86, perf: Check that current->mm is alive before getting user callchain").
I was getting this panic when running a profiling BPF program
(profile.py from bcc-tools):
[26215.051935] Kernel attempted to read user page (588) - exploit attempt? (uid: 0)
[26215.051950] BUG: Kernel NULL pointer dereference on read at 0x00000588
[26215.051952] Faulting instruction address: 0xc00000000020fac0
[26215.051957] Oops: Kernel access of bad area, sig: 11 [#1]
[...]
[26215.052049] Call Trace:
[26215.052050] [c000000061da6d30] [c00000000020fc10] perf_callchain_user_64+0x2d0/0x490 (unreliable)
[26215.052054] [c000000061da6dc0] [c00000000020f92c] perf_callchain_user+0x1c/0x30
[26215.052057] [c000000061da6de0] [c0000000005ab2a0] get_perf_callchain+0x100/0x360
[26215.052063] [c000000061da6e70] [c000000000573bc8] bpf_get_stackid+0x88/0xf0
[26215.052067] [c000000061da6ea0] [c008000000042258] bpf_prog_16d4ab9ab662f669_do_perf_event+0xf8/0x274
[...]
In addition, move storing the top-level stack entry to generic
perf_callchain_user to make sure the top-evel entry is always captured,
even if current->mm is NULL.
Fixes: 20002ded4d93 ("perf_counter: powerpc: Add callchain support")
Signed-off-by: Viktor Malik <vmalik@redhat.com>
Tested-by: Qiao Zhao <qzhao@redhat.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Saket Kumar Bhaskar <skb99@linux.ibm.com>
[Maddy: fixed message to avoid checkpatch format style error]
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260309144045.169427-1-vmalik@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/powerpc/perf/callchain.c')
| -rw-r--r-- | arch/powerpc/perf/callchain.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c index 26aa26482c9a..992cc5c98214 100644 --- a/arch/powerpc/perf/callchain.c +++ b/arch/powerpc/perf/callchain.c @@ -103,6 +103,11 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + perf_callchain_store(entry, perf_arch_instruction_pointer(regs)); + + if (!current->mm) + return; + if (!is_32bit_task()) perf_callchain_user_64(entry, regs); else |