Messages in this thread Patch in this message | | | Date | Thu, 11 Aug 2005 15:54:52 -0700 | From | Chris Wright <> | Subject | [patch 7/8] CAN-2005-2099 Destruction of failed keyring oopses |
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-stable review patch. If anyone has any objections, please let us know. ------------------
properly is destroyed without oopsing [CAN-2005-2099].
The problem occurs in three stages:
(1) The key allocator initialises the type-specific data to all zeroes. In the case of a keyring, this will become a link in the keyring name list when the keyring is instantiated.
(2) If a user (any user) attempts to add a keyring with anything other than an empty payload, the keyring instantiation function will fail with an error and won't add the keyring to the name list.
(3) The keyring's destructor then sees that the keyring has a description (name) and tries to remove the keyring from the name list, which oopses because the link pointers are both zero.
This bug permits any user to take down a box trivially.
Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Chris Wright <chrisw@osdl.org> --- security/keys/keyring.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletion(-)
Index: linux-2.6.12.y/security/keys/keyring.c =================================================================== --- linux-2.6.12.y.orig/security/keys/keyring.c +++ linux-2.6.12.y/security/keys/keyring.c @@ -188,7 +188,11 @@ static void keyring_destroy(struct key * if (keyring->description) { write_lock(&keyring_name_lock); - list_del(&keyring->type_data.link); + + if (keyring->type_data.link.next != NULL && + !list_empty(&keyring->type_data.link)) + list_del(&keyring->type_data.link); + write_unlock(&keyring_name_lock); } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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