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perf symbols: Robustify reading of build-id from sysfs 

Markus reported that perf segfaults when reading /sys/kernel/notes from
a kernel linked with GNU gold, due to what looks like a gold bug, so do
some bounds checking to avoid crashing in that case.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Report-Link: http://lkml.kernel.org/r/20161219161821.GA294@x4
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-ryhgs6a6jxvz207j2636w31c@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
hifive-unleashed-5.1
Arnaldo Carvalho de Melo 2017-01-03 15:19:21 -03:00
parent 30a9c64448
commit 7934c98a6e
1 changed files with 6 additions and 0 deletions
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6
tools/perf/util/symbol-elf.c
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@ -537,6 +537,12 @@ int sysfs__read_build_id(const char *filename, void *build_id, size_t size)
break;
} else {
int n = namesz + descsz;
if (n > (int)sizeof(bf)) {
n = sizeof(bf);
pr_debug("%s: truncating reading of build id in sysfs file %s: n_namesz=%u, n_descsz=%u.\n",
__func__, filename, nhdr.n_namesz, nhdr.n_descsz);
}
if (read(fd, bf, n) != n)
break;
}