| From foo@baz Wed Aug 22 09:42:09 CEST 2018 |
| From: Sandipan Das <sandipan@linux.ibm.com> |
| Date: Mon, 11 Jun 2018 16:10:49 +0530 |
| Subject: perf report powerpc: Fix crash if callchain is empty |
| |
| From: Sandipan Das <sandipan@linux.ibm.com> |
| |
| [ Upstream commit 143c99f6ac6812d23254e80844d6e34be897d3e1 ] |
| |
| 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 |
| |
| Before: |
| |
| # 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] |
| ... |
| |
| After: |
| |
| # perf report --branch-history |
| |
| Samples: 25 of event 'cycles:u', Event count (approx.): 2306870 |
| Overhead Source:Line Symbol Shared Object |
| + 11.60% _init+35736 [.] _init ls |
| + 9.84% strcoll_l.c:137 [.] __strcoll_l libc-2.26.so |
| + 9.16% memcpy.S:175 [.] __memcpy_power7 libc-2.26.so |
| + 9.01% gconv_charset.h:54 [.] _nl_find_locale libc-2.26.so |
| + 8.87% dl-addr.c:52 [.] _dl_addr libc-2.26.so |
| + 8.83% _init+236 [.] _init ls |
| ... |
| |
| Reported-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> |
| Signed-off-by: Sandipan Das <sandipan@linux.ibm.com> |
| Acked-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> |
| Cc: Jiri Olsa <jolsa@redhat.com> |
| Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> |
| Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> |
| Link: http://lkml.kernel.org/r/20180611104049.11048-1-sandipan@linux.ibm.com |
| Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
| Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| tools/perf/arch/powerpc/util/skip-callchain-idx.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c |
| +++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c |
| @@ -243,7 +243,7 @@ int arch_skip_callchain_idx(struct threa |
| u64 ip; |
| u64 skip_slot = -1; |
| |
| - if (chain->nr < 3) |
| + if (!chain || chain->nr < 3) |
| return skip_slot; |
| |
| ip = chain->ips[2]; |
