perf map: Fix off by one in strncpy() size argument

commit db2c549407d4a76563c579e4768f7d6d32afefba upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 63db9872c8808df8df2c87bef8d6d5cae925859e..a49f27aa0c95a5b69c90436ebec90ecade5171ee 100644 (file)
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -90,7 +90,7 @@ 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;