FAILED: patch "[PATCH] crypto: algif_skcipher - Cap recv SG list at ctx->used" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-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 7cf81954705b7e5b057f7dc39a7ded54422ab6e1 Mon Sep 17 00:00:00 2001
From: Herbert Xu <[email protected]>
Date: Fri, 29 May 2020 14:54:43 +1000
Subject: [PATCH] crypto: algif_skcipher - Cap recv SG list at ctx->used

Somewhere along the line the cap on the SG list length for receive was lost. This patch restores it and removes the subsequent test which is now redundant.

index e2c8ab408bed..4c3bdffe0c3a 100644
@@ -74,14 +74,10 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 		return PTR_ERR(areq);
 
 	/* convert iovecs of output buffers into RX SGL */
-	err = af_alg_get_rsgl(sk, msg, flags, areq, -1, &len);
+	err = af_alg_get_rsgl(sk, msg, flags, areq, ctx->used, &len);
 	if (err)
 		goto free;
 
-	/* Process only as much RX buffers for which we have TX data */
-	if (len > ctx->used)
-		len = ctx->used;
-
 	/*
 	 * If more buffers are to be expected to be processed, process only
 	 * full block size buffers.

We don't have 2d97591ef43d ("crypto: af_alg - consolidation of duplicate code") in our 4.9 and 4.4 trees.

We do carry an "out of tree" backport that fixes an issue silently fixed by 2d97591ef43d, but it does not introduce the issue that this patch fixes.

Thanks,
Sasha