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    Subject[PATCH 5.5 22/30] perf map: Fix off by one in strncpy() size argument
    Date
    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
    @@ -89,7 +89,7 @@ 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;

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