FAILED: patch "[PATCH] crypto: arm64/aes-neonbs - don't access already-freed walk.iv" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4a8108b70508df0b6c4ffa4a3974dab93dcbe851 Mon Sep 17 00:00:00 2001
From: Eric Biggers <[email protected]>
Date: Tue, 9 Apr 2019 23:46:32 -0700
Subject: [PATCH] crypto: arm64/aes-neonbs - don't access already-freed walk.iv

If the user-provided IV needs to be aligned to the algorithm's alignmask, then skcipher_walk_virt() copies the IV into a new aligned buffer walk.iv. But skcipher_walk_virt() can fail afterwards, and then if the caller unconditionally accesses walk.iv, it's a use-after-free.

xts-aes-neonbs doesn't set an alignmask, so currently it isn't affected by this despite unconditionally accessing walk.iv. However this is more subtle than desired, and unconditionally accessing walk.iv has caused a real problem in other algorithms. Thus, update xts-aes-neonbs to start checking the return value of skcipher_walk_virt().

index 4737b6c6c5cf..514455117733 100644
@@ -304,6 +304,8 @@ static int __xts_crypt(struct skcipher_request *req,
 	int err;
 
 	err = skcipher_walk_virt(&walk, req, false);
+	if (err)
+		return err;
 
 	kernel_neon_begin();
 	neon_aes_ecb_encrypt(walk.iv, walk.iv, ctx->twkey, ctx->key.rounds, 1);