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52 lines
1.6 KiB
Diff
52 lines
1.6 KiB
Diff
From dc4a2f40de419c01b538c87f6bdfc15d574d9f7e Mon Sep 17 00:00:00 2001
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From: Sasha Levin <sasha.levin@oracle.com>
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Date: Mon, 29 Dec 2014 09:39:01 -0500
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Subject: KEYS: close race between key lookup and freeing
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commit a3a8784454692dd72e5d5d34dcdab17b4420e74c upstream.
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When a key is being garbage collected, it's key->user would get put before
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the ->destroy() callback is called, where the key is removed from it's
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respective tracking structures.
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This leaves a key hanging in a semi-invalid state which leaves a window open
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for a different task to try an access key->user. An example is
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find_keyring_by_name() which would dereference key->user for a key that is
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in the process of being garbage collected (where key->user was freed but
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->destroy() wasn't called yet - so it's still present in the linked list).
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This would cause either a panic, or corrupt memory.
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Fixes CVE-2014-9529.
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Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
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Signed-off-by: David Howells <dhowells@redhat.com>
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[bwh: Backported to 3.2: adjust indentation]
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Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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---
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security/keys/gc.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/security/keys/gc.c b/security/keys/gc.c
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index bf4d8da..2e2395d 100644
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--- a/security/keys/gc.c
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+++ b/security/keys/gc.c
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@@ -186,12 +186,12 @@ static noinline void key_gc_unused_key(struct key *key)
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if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
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atomic_dec(&key->user->nikeys);
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- key_user_put(key->user);
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-
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/* now throw away the key memory */
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if (key->type->destroy)
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key->type->destroy(key);
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+ key_user_put(key->user);
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+
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kfree(key->description);
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#ifdef KEY_DEBUGGING
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--
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cgit v1.1
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