Commit 8767ba27 authored Jan 08, 2010 by Masami Hiramatsu Committed by Linus Torvalds Jan 11, 2010

kmod: fix resource leak in call_usermodehelper_pipe()



Fix resource (write-pipe file) leak in call_usermodehelper_pipe().

When call_usermodehelper_exec() fails, write-pipe file is opened and
call_usermodehelper_pipe() just returns an error.  Since it is hard for
caller to determine whether the error occured when opening the pipe or
executing the helper, the caller cannot close the pipe by themselves.

I've found this resoruce leak when testing coredump.  You can check how
the resource leaks as below;

$ echo "|nocommand" > /proc/sys/kernel/core_pattern
$ ulimit -c unlimited
$ while [ 1 ]; do ./segv; done &> /dev/null &
$ cat /proc/meminfo (<- repeat it)

where segv.c is;
//-----
int main () {
        char *p = 0;
        *p = 1;
}
//-----

This patch closes write-pipe file if call_usermodehelper_exec() failed.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 42d53b4f

kernel/kmod.c

+7 −5

Original line number	Diff line number	Diff line
		@@ -520,13 +520,15 @@ int call_usermodehelper_pipe(char path, char argv, char *envp,
		return -ENOMEM;

		ret = call_usermodehelper_stdinpipe(sub_info, filp);
		if (ret < 0)
		goto out;
		if (ret < 0) {
		call_usermodehelper_freeinfo(sub_info);
		return ret;
		}

		return call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
		ret = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
		if (ret < 0) /* Failed to execute helper, close pipe */
		filp_close(*filp, NULL);

		out:
		call_usermodehelper_freeinfo(sub_info);
		return ret;
		}
		EXPORT_SYMBOL(call_usermodehelper_pipe);

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