From: Viktor Malik <vmalik@redhat.com> mainline inclusion from mainline-v7.0-rc4 commit e9bbfb4bfa86c6b5515b868d6982ac60505d7e39 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/14975 CVE: CVE-2026-43416 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... ---------------------------------------------------------------------- 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 Conflicts: arch/powerpc/perf/callchain.c arch/powerpc/perf/callchain_32.c arch/powerpc/perf/callchain_64.c [Fix context conflicts.] Signed-off-by: Luo Gengkun <luogengkun2@huawei.com> --- arch/powerpc/perf/callchain.c | 5 +++++ arch/powerpc/perf/callchain_32.c | 1 - arch/powerpc/perf/callchain_64.c | 1 - 3 files changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c index 6b4434dd0ff3..3727da624dbb 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_instruction_pointer(regs)); + + if (!current->mm) + return; + if (!is_32bit_task()) perf_callchain_user_64(entry, regs); else diff --git a/arch/powerpc/perf/callchain_32.c b/arch/powerpc/perf/callchain_32.c index ea8cfe3806dc..d6ab21b52fa4 100644 --- a/arch/powerpc/perf/callchain_32.c +++ b/arch/powerpc/perf/callchain_32.c @@ -142,7 +142,6 @@ void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry, next_ip = perf_instruction_pointer(regs); lr = regs->link; sp = regs->gpr[1]; - perf_callchain_store(entry, next_ip); while (entry->nr < entry->max_stack) { fp = (unsigned int __user *) (unsigned long) sp; diff --git a/arch/powerpc/perf/callchain_64.c b/arch/powerpc/perf/callchain_64.c index 488e8a21a11e..55e1fb899f96 100644 --- a/arch/powerpc/perf/callchain_64.c +++ b/arch/powerpc/perf/callchain_64.c @@ -77,7 +77,6 @@ void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry, next_ip = perf_instruction_pointer(regs); lr = regs->link; sp = regs->gpr[1]; - perf_callchain_store(entry, next_ip); while (entry->nr < entry->max_stack) { fp = (unsigned long __user *) sp; -- 2.34.1