Attachment 625178 Details for Bug 912202

[patch] 0001-KEYS-close-race-between-key-lookup-and-freeing.patch

0001-KEYS-close-race-between-key-lookup-and-freeing.patch (text/plain), 1.70 KB, created by Joey Lee on 2015-03-03 10:25:20 UTC

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Creator: Joey Lee

Created: 2015-03-03 10:25:20 UTC

Size: 1.70 KB

patch

obsolete

>From a3a8784454692dd72e5d5d34dcdab17b4420e74c Mon Sep 17 00:00:00 2001
>From: Sasha Levin <sasha.levin@oracle.com>
>Date: Mon, 29 Dec 2014 09:39:01 -0500
>Subject: [PATCH] KEYS: close race between key lookup and freeing
>
>When a key is being garbage collected, it's key->user would get put before
>the ->destroy() callback is called, where the key is removed from it's
>respective tracking structures.
>
>This leaves a key hanging in a semi-invalid state which leaves a window open
>for a different task to try an access key->user. An example is
>find_keyring_by_name() which would dereference key->user for a key that is
>in the process of being garbage collected (where key->user was freed but
>->destroy() wasn't called yet - so it's still present in the linked list).
>
>This would cause either a panic, or corrupt memory.
>
>Fixes CVE-2014-9529.
>
>Backport to v3.0:
>There have similar codes in key.c in v3.0, so backported this patch.
>commit id: a3a8784454692dd72e5d5d34dcdab17b4420e74c
>
>Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
>Signed-off-by: David Howells <dhowells@redhat.com>
>Cc: Jiri Slaby <jslaby@suse.cz>
>Signed-off-by: Lee, Chun-Yi <jlee@suse.com>
>---
> security/keys/gc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>Index: linux2/security/keys/key.c
>===================================================================
>--- linux2.orig/security/keys/key.c
>+++ linux2/security/keys/key.c
>@@ -639,12 +639,12 @@ found_dead_key:
> 	if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
> 		atomic_dec(&key->user->nikeys);
> 
>-	key_user_put(key->user);
>-
> 	/* now throw away the key memory */
> 	if (key->type->destroy)
> 		key->type->destroy(key);
> 
>+	key_user_put(key->user);
>+
> 	kfree(key->description);
> 
> #ifdef KEY_DEBUGGING

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Attachments on bug 912202: 620470 | 625178 | 625290