Patch "KEYS: Change the name of the dead type to ".dead" to prevent user access" has been added to the 4.4-stable tree
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This is a note to let you know that I've just added the patch titled
KEYS: Change the name of the dead type to ".dead" to prevent user access
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
keys-change-the-name-of-the-dead-type-to-.dead-to-prevent-user-access.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.
Quoted 1 line
From
c1644fe041ebaf6519f6809146a77c3ead9193afMon Sep 17 00:00:00 2001
From: David Howells <[email protected]>
Date: Tue, 18 Apr 2017 15:31:08 +0100
Subject: KEYS: Change the name of the dead type to ".dead" to prevent user access
From: David Howells <[email protected]>
commit c1644fe041ebaf6519f6809146a77c3ead9193af upstream.
This fixes CVE-2017-6951.
Userspace should not be able to do things with the "dead" key type as it doesn't have some of the helper functions set upon it that the kernel needs. Attempting to use it may cause the kernel to crash.
Fix this by changing the name of the type to ".dead" so that it's rejected up front on userspace syscalls by key_get_type_from_user().
Though this doesn't seem to affect recent kernels, it does affect older ones, certainly those prior to:
commit c06cfb08b88dfbe13be44a69ae2fdc3a7c902d81 Author: David Howells <[email protected]> Date: Tue Sep 16 17:36:06 2014 +0100 KEYS: Remove key_type::match in favour of overriding default by match_preparse
which went in before 3.18-rc1.
--- security/keys/gc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
security/keys/gc.c +1 -1
@@ -46,7 +46,7 @@ static unsigned long key_gc_flags;* immediately unlinked. */ struct key_type key_type_dead = { - .name ="dead" , + .name =".dead" , };/*
Patches currently in stable-queue which might be from [email protected] are
queue-4.4/keys-disallow-keyrings-beginning-with-.-to-be-joined-as-session-keyrings.patch queue-4.4/keys-change-the-name-of-the-dead-type-to-.dead-to-prevent-user-access.patch queue-4.4/keys-fix-keyctl_set_reqkey_keyring-to-not-leak-thread-keyrings.patch