From 70a2cba972e5e4a5d850e4179381f1cd344c6828 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Tue, 19 Apr 2016 11:17:27 +0300 Subject: [PATCH] perf buildid: Fix off-by-one in write_buildid() write_buildid() increments 'name_len' with intention to take into account trailing zero byte. However, 'name_len' was already incremented in machine__write_buildid_table() before. So this leads to out-of-bounds read in do_write(): $ ./perf record sleep 0 [ perf record: Woken up 1 times to write data ] ================================================================= ==15899==ERROR: AddressSanitizer: global-buffer-overflow on address 0x00000099fc92 at pc 0x7f1aa9c7eab5 bp 0x7fff940f84d0 sp 0x7fff940f7c78 READ of size 19 at 0x00000099fc92 thread T0 #0 0x7f1aa9c7eab4 (/usr/lib/gcc/x86_64-pc-linux-gnu/5.3.0/libasan.so.2+0x44ab4) #1 0x649c5b in do_write util/header.c:67 #2 0x649c5b in write_padded util/header.c:82 #3 0x57e8bc in write_buildid util/build-id.c:239 #4 0x57e8bc in machine__write_buildid_table util/build-id.c:278 ... 0x00000099fc92 is located 0 bytes to the right of global variable '*.LC99' defined in 'util/symbol.c' (0x99fc80) of size 18 '*.LC99' is ascii string '[kernel.kallsyms]' ... Shadow bytes around the buggy address: 0x00008012bf80: f9 f9 f9 f9 00 00 00 00 00 00 03 f9 f9 f9 f9 f9 =>0x00008012bf90: 00 00[02]f9 f9 f9 f9 f9 00 00 00 00 00 05 f9 f9 0x00008012bfa0: f9 f9 f9 f9 00 03 f9 f9 f9 f9 f9 f9 00 00 00 00 Signed-off-by: Andrey Ryabinin Cc: Alexander Shishkin Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1461053847-5633-1-git-send-email-aryabinin@virtuozzo.com [ Remove the off-by one at the origin, to keep len(s) == strlen(s) assumption ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/build-id.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c index 0573c2ec861d..b6ecf87bc3e3 100644 --- a/tools/perf/util/build-id.c +++ b/tools/perf/util/build-id.c @@ -261,14 +261,14 @@ static int machine__write_buildid_table(struct machine *machine, int fd) if (dso__is_vdso(pos)) { name = pos->short_name; - name_len = pos->short_name_len + 1; + name_len = pos->short_name_len; } else if (dso__is_kcore(pos)) { machine__mmap_name(machine, nm, sizeof(nm)); name = nm; - name_len = strlen(nm) + 1; + name_len = strlen(nm); } else { name = pos->long_name; - name_len = pos->long_name_len + 1; + name_len = pos->long_name_len; } in_kernel = pos->kernel || -- 2.39.5