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

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: eca8183 ("perf tools: Add automatic remapping of Android libraries")
Signed-off-by: disconnect3d <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Changbin Du <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Keeping <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Michael Lentine <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: disconnect3d

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;