usermodehelper: cleanup/fix __orderly_poweroff() && argv_free()

__orderly_poweroff() does argv_free() if call_usermodehelper_fns()
returns -ENOMEM.  As Lucas pointed out, this can be wrong if -ENOMEM was
not triggered by the failing call_usermodehelper_setup(), in this case
both __orderly_poweroff() and argv_cleanup() can do kfree().

Kill argv_cleanup() and change __orderly_poweroff() to call argv_free()
unconditionally like do_coredump() does.  This info->cleanup() is not
needed (and wrong) since 6c0c0d4d "fix bug in orderly_poweroff() which
did the UMH_NO_WAIT => UMH_WAIT_EXEC change, we can rely on the fact
that CLONE_VFORK can't return until do_execve() succeeds/fails.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: hongfeng <hongfeng@marvell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/sys.c b/kernel/sys.c
index e10566bee39967394b05c42effce1e56cb6b76f6..81f56445fba949790b34b7bf3f97383555134672 100644 (file)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2185,11 +2185,6 @@ SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
 
 char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
 
-static void argv_cleanup(struct subprocess_info *info)
-{
-       argv_free(info->argv);
-}
-
 static int __orderly_poweroff(void)
 {
        int argc;
@@ -2209,9 +2204,8 @@ static int __orderly_poweroff(void)
        }
 
        ret = call_usermodehelper_fns(argv[0], argv, envp, UMH_WAIT_EXEC,
-                                     NULL, argv_cleanup, NULL);
-       if (ret == -ENOMEM)
-               argv_free(argv);
+                                     NULL, NULL, NULL);
+       argv_free(argv);
 
        return ret;
 }