Messages in this thread | | | Subject | Re: [PATCH] perf report powerpc: Fix crash if callchain is empty | From | Ravi Bangoria <> | Date | Tue, 12 Jun 2018 09:28:09 +0530 |
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On 06/11/2018 04:10 PM, Sandipan Das wrote: > 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 applying this patch: > > # 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 applying this patch: > > # 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>
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