4.4-stable review patch. If anyone has any objections, please let me know.
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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];