From: disconnect3d <dominik.b.czarnota@gmail.com>

Date: Mon, 9 Mar 2020 11:48:53 +0100

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

Git-commit: db2c549407d4a76563c579e4768f7d6d32afefba

Patch-mainline: v5.6

References: git-fixes

​

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: Tony Jones <tonyj@suse.de>

---

 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;

​

​