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    Subject[28/38] exec: do not call request_module() twice from search_binary_handler()
    3.0-stable review patch.  If anyone has any objections, please let us know.

    ------------------

    From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

    commit 912193521b719fbfc2f16776febf5232fe8ba261 upstream.

    Currently, search_binary_handler() tries to load binary loader module
    using request_module() if a loader for the requested program is not yet
    loaded. But second attempt of request_module() does not affect the result
    of search_binary_handler().

    If request_module() triggered recursion, calling request_module() twice
    causes 2 to the power of MAX_KMOD_CONCURRENT (= 50) repetitions. It is
    not an infinite loop but is sufficient for users to consider as a hang up.

    Therefore, this patch changes not to call request_module() twice, making 1
    to the power of MAX_KMOD_CONCURRENT repetitions in case of recursion.

    Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
    Reported-by: Richard Weinberger <richard@nod.at>
    Tested-by: Richard Weinberger <richard@nod.at>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Cc: Maxim Uvarov <muvarov@gmail.com>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

    ---
    fs/exec.c | 2 ++
    1 file changed, 2 insertions(+)

    --- a/fs/exec.c
    +++ b/fs/exec.c
    @@ -1411,6 +1411,8 @@ int search_binary_handler(struct linux_b
    printable(bprm->buf[2]) &&
    printable(bprm->buf[3]))
    break; /* -ENOEXEC */
    + if (try)
    + break; /* -ENOEXEC */
    request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
    #endif
    }



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