Commit 91219352 authored Jul 26, 2011 by Tetsuo Handa Committed by Linus Torvalds Jul 26, 2011

exec: do not call request_module() twice from search_binary_handler()



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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent aacb3d17

fs/exec.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1440,6 +1440,8 @@ int search_binary_handler(struct linux_binprm bprm,struct pt_regs regs)
		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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