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Subject[PATCH 07/23] perf map: Fix off by one in strncpy() size argument
Date
From: disconnect3d <dominik.b.czarnota@gmail.com>

This patch fixes an off-by-one error in strncpy size argument in
tools/perf/util/map.c. The issue is that in:

strncmp(filename, "/system/lib/", 11)

the passed string literal: "/system/lib/" has 12 bytes (without the NULL
byte) and the passed size argument is 11. As a result, the logic won't
match the ending "/" byte and will pass filepaths that are stored in
other directories e.g. "/system/libmalicious/bin" or just
"/system/libmalicious".

This functionality seems to be present only on Android. I assume the
/system/ directory is only writable by the root user, so I don't think
this bug has much (or any) security impact.

Fixes: eca818369996 ("perf tools: Add automatic remapping of Android libraries")
Signed-off-by: disconnect3d <dominik.b.czarnota@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Changbin Du <changbin.du@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Keeping <john@metanate.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Lentine <mlentine@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20200309104855.3775-1-dominik.b.czarnota@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/map.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 95428511300d..b342f744b1fc 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -89,7 +89,7 @@ static inline bool replace_android_lib(const char *filename, char *newfilename)
return true;
}

- if (!strncmp(filename, "/system/lib/", 11)) {
+ if (!strncmp(filename, "/system/lib/", 12)) {
char *ndk, *app;
const char *arch;
size_t ndk_length;
--
2.21.1
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