This is a note to let you know that I've just added the patch titled
fscrypt: fix dereference of NULL user_key_payload
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:
fscrypt-fix-dereference-of-null-user_key_payload.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 <stable@xxxxxxxxxxxxxxx> know about it.
>From d60b5b7854c3d135b869f74fb93eaf63cbb1991a Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@xxxxxxxxxx>
Date: Mon, 9 Oct 2017 12:46:18 -0700
Subject: fscrypt: fix dereference of NULL user_key_payload
From: Eric Biggers <ebiggers@xxxxxxxxxx>
commit d60b5b7854c3d135b869f74fb93eaf63cbb1991a upstream.
When an fscrypt-encrypted file is opened, we request the file's master
key from the keyrings service as a logon key, then access its payload.
However, a revoked key has a NULL payload, and we failed to check for
this. request_key() *does* skip revoked keys, but there is still a
window where the key can be revoked before we acquire its semaphore.
Fix it by checking for a NULL payload, treating it like a key which was
already revoked at the time it was requested.
Fixes: 88bd6ccdcdd6 ("ext4 crypto: add encryption key management facilities")
Reviewed-by: James Morris <james.l.morris@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [v4.1+]
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/crypto_key.c | 6 ++++++
fs/f2fs/crypto_key.c | 6 ++++++
2 files changed, 12 insertions(+)
--- a/fs/ext4/crypto_key.c
+++ b/fs/ext4/crypto_key.c
@@ -204,6 +204,12 @@ int ext4_get_encryption_info(struct inod
}
down_read(&keyring_key->sem);
ukp = user_key_payload(keyring_key);
+ if (!ukp) {
+ /* key was revoked before we acquired its semaphore */
+ res = -EKEYREVOKED;
+ up_read(&keyring_key->sem);
+ goto out;
+ }
if (ukp->datalen != sizeof(struct ext4_encryption_key)) {
res = -EINVAL;
up_read(&keyring_key->sem);
--- a/fs/f2fs/crypto_key.c
+++ b/fs/f2fs/crypto_key.c
@@ -195,6 +195,12 @@ int f2fs_get_encryption_info(struct inod
}
down_read(&keyring_key->sem);
ukp = user_key_payload(keyring_key);
+ if (!ukp) {
+ /* key was revoked before we acquired its semaphore */
+ res = -EKEYREVOKED;
+ up_read(&keyring_key->sem);
+ goto out;
+ }
if (ukp->datalen != sizeof(struct f2fs_encryption_key)) {
res = -EINVAL;
up_read(&keyring_key->sem);
Patches currently in stable-queue which might be from ebiggers@xxxxxxxxxx are
queue-4.4/keys-fix-race-between-updating-and-finding-a-negative-key.patch
queue-4.4/fscrypto-require-write-access-to-mount-to-set-encryption-policy.patch
queue-4.4/fs-cache-fix-dereference-of-null-user_key_payload.patch
queue-4.4/lib-digsig-fix-dereference-of-null-user_key_payload.patch
queue-4.4/fscrypt-fix-dereference-of-null-user_key_payload.patch
queue-4.4/f2fs-crypto-add-missing-locking-for-keyring_key-access.patch
queue-4.4/keys-encrypted-fix-dereference-of-null-user_key_payload.patch
queue-4.4/f2fs-crypto-replace-some-bug_on-s-with-error-checks.patch
queue-4.4/keys-don-t-let-add_key-update-an-uninstantiated-key.patch