From c58c49ac630979a285d574b3f72a528209515fb3 Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Tue, 7 Jun 2016 03:54:38 +0000 Subject: [PATCH] perf tools: Fix crash in build_id_cache__kallsyms_path() build_id_cache__kallsyms_path() accepts a string buffer but also allocs a buffer using asnprintf. Unfortunately, the its only user passes it a stack-allocated buffer. Freeing it causes crashes like this: $ perf script *** Error in `/home/wangnan/perf': free(): invalid pointer: 0x00007fffffff9630 *** ======= Backtrace: ========= lib64/libc.so.6(+0x6eeef)[0x7ffff5dbaeef] lib64/libc.so.6(+0x78cae)[0x7ffff5dc4cae] lib64/libc.so.6(+0x79987)[0x7ffff5dc5987] /home/w00229757/perf(build_id_cache__kallsyms_path+0x6b)[0x49681b] /home/w00229757/perf[0x4bdd40] /home/w00229757/perf(dso__load+0xa3a)[0x4c048a] /home/w00229757/perf(map__load+0x6f)[0x4d561f] /home/w00229757/perf(thread__find_addr_map+0x235)[0x49e935] /home/w00229757/perf(machine__resolve+0x7d)[0x49ec6d] /home/w00229757/perf[0x4555a8] /home/w00229757/perf[0x4d9507] /home/w00229757/perf[0x4d9e80] /home/w00229757/perf(ordered_events__flush+0x354)[0x4dd444] /home/w00229757/perf(perf_session__process_events+0x3d0)[0x4dc140] /home/w00229757/perf(cmd_script+0x12b0)[0x4592e0] /home/w00229757/perf[0x4911f1] /home/w00229757/perf(main+0x68f)[0x4352ef] /lib64/libc.so.6(__libc_start_main+0xf5)[0x7ffff5d6dbd5] /home/w00229757/perf[0x435415] ======= Memory map: ======== This patch simplifies build_id_cache__kallsyms_path(), not even considering allocating a string buffer, so never frees anything. Its caller should manage memory allocation. Signed-off-by: Wang Nan Cc: Masami Hiramatsu Cc: Zefan Li Cc: pi3orama@163.com Fixes: 01412261d994 ("perf buildid-cache: Use path/to/bin/buildid/elf instead of path/to/bin/buildid") Link: http://lkml.kernel.org/r/1465271678-7392-1-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/build-id.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c index 67f986c..20aef90 100644 --- a/tools/perf/util/build-id.c +++ b/tools/perf/util/build-id.c @@ -147,20 +147,17 @@ static int asnprintf(char **strp, size_t size, const char *fmt, ...) char *build_id_cache__kallsyms_path(const char *sbuild_id, char *bf, size_t size) { - bool is_alloc = !!bf; bool retry_old = true; - asnprintf(&bf, size, "%s/%s/%s/kallsyms", - buildid_dir, DSO__NAME_KALLSYMS, sbuild_id); + snprintf(bf, size, "%s/%s/%s/kallsyms", + buildid_dir, DSO__NAME_KALLSYMS, sbuild_id); retry: if (!access(bf, F_OK)) return bf; - if (is_alloc) - free(bf); if (retry_old) { /* Try old style kallsyms cache */ - asnprintf(&bf, size, "%s/%s/%s", - buildid_dir, DSO__NAME_KALLSYMS, sbuild_id); + snprintf(bf, size, "%s/%s/%s", + buildid_dir, DSO__NAME_KALLSYMS, sbuild_id); retry_old = false; goto retry; } -- 2.7.4