[PATCH] set*uid() must not fail-and-return on OOM/rlimits

[Solar Designer <solar@openwall.com>]

Willy and all,

Attached is a trivial patch (extracted from 2.4.33-ow1) that makes
set*uid() kill the current process rather than proceed with -EAGAIN when
the kernel is running out of memory.  Apparently, alloc_uid() can't fail
and return anyway due to properties of the allocator, in which case the
patch does not change a thing.  But better safe than sorry.

As you're probably aware, 2.6 kernels are affected to a greater extent,
where set*uid() may also fail on trying to exceed RLIMIT_NPROC.  That
needs to be fixed, too.

Opinions are welcome.

Thanks,

Alexander

diff -urpPX nopatch linux-2.4.33/kernel/sys.c linux/kernel/sys.c
--- linux-2.4.33/kernel/sys.c	Fri Nov 28 21:26:21 2003
+++ linux/kernel/sys.c	Wed Aug 16 05:19:21 2006
@@ -514,8 +514,10 @@ static int set_user(uid_t new_ruid, int 
 	struct user_struct *new_user;
 
 	new_user = alloc_uid(new_ruid);
-	if (!new_user)
+	if (!new_user) {
+		force_sig(SIGSEGV, current);
 		return -EAGAIN;
+	}
 	switch_uid(new_user);
 
 	if(dumpclear)