linux-kernel - [PATCH] Fix infinite loop in search_binary

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Date:	Fri, 17 Jun 2011 00:11:20 +0200
From:	Richard Weinberger <richard@....at>
To:	viro@...iv.linux.org.uk
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	user-mode-linux-devel@...ts.sourceforge.net,
	Richard Weinberger <richard@....at>
Subject: [PATCH] Fix infinite loop in search_binary_handler()

When search_binary_handler() is called to find a handler
for /sbin/modprobe it will end up in an infinite loop because
it executes request_module() to load a binfmt module with
/sbin/modprobe...

Running a x86_64 kernel without ia32 emulation and a x86 user land
triggers this issue.

Signed-off-by: Richard Weinberger <richard@....at>
---
 fs/exec.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 97e0d52..7271b22 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1411,7 +1411,10 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 			    printable(bprm->buf[2]) &&
 			    printable(bprm->buf[3]))
 				break; /* -ENOEXEC */
-			request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
+
+			/* Avoid an infinite loop */
+			if (strcmp(modprobe_path, bprm->filename))
+				request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
 #endif
 		}
 	}
-- 
1.7.5.4

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