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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        disconnect3d <dominik.b.czarnota@gmail.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Changbin Du <changbin.du@intel.com>,
        Jiri Olsa <jolsa@redhat.com>, John Keeping <john@metanate.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Michael Lentine <mlentine@google.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Song Liu <songliubraving@fb.com>,
        Stephane Eranian <eranian@google.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: [PATCH 4.9 102/102] perf map: Fix off by one in strncpy() size argument
Date:   Wed,  1 Apr 2020 18:18:45 +0200
Message-Id: <20200401161549.020442250@linuxfoundation.org>
In-Reply-To: <20200401161530.451355388@linuxfoundation.org>
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From: disconnect3d <dominik.b.czarnota@gmail.com>

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>

---
 tools/perf/util/map.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -88,7 +88,7 @@ static inline bool replace_android_lib(c
 		return true;
 	}
 
-	if (!strncmp(filename, "/system/lib/", 11)) {
+	if (!strncmp(filename, "/system/lib/", 12)) {
 		char *ndk, *app;
 		const char *arch;
 		size_t ndk_length;