For some cases, the callchain provided by the kernel may be
empty. So, the callchain ip filtering code will cause a crash
if we do not check whether the struct ip_callchain pointer is
NULL before accessing any members.
This can be observed on a powerpc64le system running Fedora 27
as shown below.
# perf record -b -e cycles:u ls
# perf report --branch-history
perf: Segmentation fault
-------- backtrace --------
perf[0x1027615c]
linux-vdso64.so.1(__kernel_sigtramp_rt64+0x0)[0x7fff856304d8]
perf(arch_skip_callchain_idx+0x44)[0x10257c58]
perf[0x1017f2e4]
perf(thread__resolve_callchain+0x124)[0x1017ff5c]
perf(sample__resolve_callchain+0xf0)[0x10172788]
...
Reported-by: Ravi Bangoria <ravi.bango...@linux.vnet.ibm.com>
Signed-off-by: Sandipan Das <sandi...@linux.vnet.ibm.com>
---
tools/perf/arch/powerpc/util/skip-callchain-idx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/arch/powerpc/util/skip-callchain-idx.c
b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
index d3a13f79d3ee..910db8762120 100644
--- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c
+++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
@@ -262,7 +262,7 @@ int arch_skip_callchain_idx(struct thread *thread, struct
ip_callchain *chain)
int rc;
u64 skip_slot = -1;
- if (chain->nr < 3)
+ if (!chain || chain->nr < 3)
return skip_slot;
rc = check_return_addr(thread, chain->ips[1]);
--
2.14.3
