Patch "crypto: xts,lrw - fix out-of-bounds write after kmalloc failure" has been added to the 4.10-stable tree

This is a note to let you know that I've just added the patch titled

crypto: xts,lrw - fix out-of-bounds write after kmalloc failure

to the 4.10-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-xts-lrw-fix-out-of-bounds-write-after-kmalloc-failure.patch
and it can be found in the queue-4.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Biggers <[email protected]>
Date: Thu, 23 Mar 2017 13:39:46 -0700
Subject: crypto: xts,lrw - fix out-of-bounds write after kmalloc failure

From: Eric Biggers <[email protected]>

commit 9df0eb180c2074451f25556eb566d89c7057c2ac upstream.

In the generic XTS and LRW algorithms, for input data > 128 bytes, a temporary buffer is allocated to hold the values to be XOR'ed with the data before and after encryption or decryption. If the allocation fails, the fixed-size buffer embedded in the request buffer is meant to be used as a fallback --- resulting in more calls to the ECB algorithm, but still producing the correct result. However, we weren't correctly limiting subreq->cryptlen in this case, resulting in pre_crypt() overrunning the embedded buffer. Fix this by setting subreq->cryptlen correctly.

---
 crypto/lrw.c |    7 +++++--
 crypto/xts.c |    7 +++++--
 2 files changed, 10 insertions(+), 4 deletions(-)

@@ -286,8 +286,11 @@ static int init_crypt(struct skcipher_re
 
 	subreq->cryptlen = LRW_BUFFER_SIZE;
 	if (req->cryptlen > LRW_BUFFER_SIZE) {
-		subreq->cryptlen = min(req->cryptlen, (unsigned)PAGE_SIZE);
-		rctx->ext = kmalloc(subreq->cryptlen, gfp);
+		unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
+
+		rctx->ext = kmalloc(n, gfp);
+		if (rctx->ext)
+			subreq->cryptlen = n;
 	}
 
 	rctx->src = req->src;

@@ -230,8 +230,11 @@ static int init_crypt(struct skcipher_re
 
 	subreq->cryptlen = XTS_BUFFER_SIZE;
 	if (req->cryptlen > XTS_BUFFER_SIZE) {
-		subreq->cryptlen = min(req->cryptlen, (unsigned)PAGE_SIZE);
-		rctx->ext = kmalloc(subreq->cryptlen, gfp);
+		unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
+
+		rctx->ext = kmalloc(n, gfp);
+		if (rctx->ext)
+			subreq->cryptlen = n;
 	}
 
 	rctx->src = req->src;

Patches currently in stable-queue which might be from [email protected] are

queue-4.10/crypto-xts-lrw-fix-out-of-bounds-write-after-kmalloc-failure.patch