Re: SEVERE Problems in 2.5.12 at uid0 access

[Paul Larson <plars@austin.ibm.com>]

On Wed, 2002-05-01 at 13:18, Alexander Viro wrote:
> Yes, it is.  Look for the patch I've posted yesterday (subject was
> something like "[PATCH] missing checks", IIRC).

Before I found this message I was also trying to hunt down this problem
after noticing that 2.5.12 failed unlink08 from LTP.  The thing I think
broke it though was a seemlingly minor change to the handling of the
return value from exec_permission_lite in link_path_walk().  In 2.5.11
it rechecked with permission() if it got an error back from
exec_permission_lite(), but in 2.5.12 it only does this if err ==
-EAGAIN.  This patch also seems to fix the problem, and simply reverts
it back to the original way it was handled rather than adding more code
to exec_permission_lite().  I'll let you decide which is the best way.

Thanks,
Paul Larson

--- linux/fs/namei.c	Thu May  2 18:36:01 2002
+++ linux-fix/fs/namei.c	Thu May  2 18:36:17 2002
@@ -573,7 +573,7 @@
 		unsigned int c;
 
 		err = exec_permission_lite(inode);
-		if (err == -EAGAIN) {
+		if (err) {
 			unlock_nd(nd);
 			err = permission(inode, MAY_EXEC);
 			lock_nd(nd);