[PATCH] Fix ____call_usermodehelper errors being silently ignored (111dbe0c) · Commits · 戴 / test

If ____call_usermodehelper fails, we're not interested in the child process' exit value, but the real error, so let's stop wait_for_helper from overwriting it in that case. Issue discovered by Benedikt Böhm while working on a Linux-VServer usermode helper. Signed-off-by:

Björn Steinbrink <B.Steinbrink@gmx.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

kernel/kmod.c

+11 −1

Original line number	Diff line number	Diff line
		@@ -176,6 +176,8 @@ static int wait_for_helper(void *data)
		if (pid < 0) {
		sub_info->retval = pid;
		} else {
		int ret;

		/*
		* Normally it is bogus to call wait4() from in-kernel because
		* wait4() wants to write the exit code to a userspace address.
		@@ -185,7 +187,15 @@ static int wait_for_helper(void *data)
		*
		* Thus the __user pointer cast is valid here.
		*/
		sys_wait4(pid, (int __user *) &sub_info->retval, 0, NULL);
		sys_wait4(pid, (int __user *)&ret, 0, NULL);

		/*
		* If ret is 0, either ____call_usermodehelper failed and the
		* real error code is already in sub_info->retval or
		* sub_info->retval is 0 anyway, so don't mess with it then.
		*/
		if (ret)
		sub_info->retval = ret;
		}

		complete(sub_info->complete);

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