From 912193521b719fbfc2f16776febf5232fe8ba261 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Tue, 26 Jul 2011 16:08:41 -0700
Subject: 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>
---
fs/exec.c | 2 ++
1 file changed, 2 insertions(+)
(limited to 'fs')
diff --git a/fs/exec.c b/fs/exec.c
index 01829a1cb766..e6770a526f34 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -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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