This is a note to let you know that I've just added the patch titled
crypto: af_alg - fix backlog handling
to the 3.17-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:
crypto-af_alg-fix-backlog-handling.patch
and it can be found in the queue-3.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7e77bdebff5cb1e9876c561f69710b9ab8fa1f7e Mon Sep 17 00:00:00 2001
From: Rabin Vincent <rabin.vincent@xxxxxxxx>
Date: Fri, 19 Dec 2014 13:36:08 +0100
Subject: crypto: af_alg - fix backlog handling
From: Rabin Vincent <rabin.vincent@xxxxxxxx>
commit 7e77bdebff5cb1e9876c561f69710b9ab8fa1f7e upstream.
If a request is backlogged, it's complete() handler will get called
twice: once with -EINPROGRESS, and once with the final error code.
af_alg's complete handler, unlike other users, does not handle the
-EINPROGRESS but instead always completes the completion that recvmsg()
is waiting on. This can lead to a return to user space while the
request is still pending in the driver. If userspace closes the sockets
before the requests are handled by the driver, this will lead to
use-after-frees (and potential crashes) in the kernel due to the tfm
having been freed.
The crashes can be easily reproduced (for example) by reducing the max
queue length in cryptod.c and running the following (from
http://www.chronox.de/libkcapi.html) on AES-NI capable hardware:
$ while true; do kcapi -x 1 -e -c '__ecb-aes-aesni' \
-k 00000000000000000000000000000000 \
-p 00000000000000000000000000000000 >/dev/null & done
Signed-off-by: Rabin Vincent <rabin.vincent@xxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
crypto/af_alg.c | 3 +++
1 file changed, 3 insertions(+)
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -449,6 +449,9 @@ void af_alg_complete(struct crypto_async
{
struct af_alg_completion *completion = req->data;
+ if (err == -EINPROGRESS)
+ return;
+
completion->err = err;
complete(&completion->completion);
}
Patches currently in stable-queue which might be from rabin.vincent@xxxxxxxx are
queue-3.17/crypto-af_alg-fix-backlog-handling.patch
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