Patch "target/iscsi: avoid NULL dereference in CHAP auth error path" has been added to the 4.15-stable tree

[<gregkh@linuxfoundation.org>]

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

    target/iscsi: avoid NULL dereference in CHAP auth error path

to the 4.15-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:
     target-iscsi-avoid-null-dereference-in-chap-auth-error-path.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ce512d79d0466a604793addb6b769d12ee326822 Mon Sep 17 00:00:00 2001
From: David Disseldorp <ddiss@suse.de>
Date: Wed, 13 Dec 2017 18:22:30 +0100
Subject: target/iscsi: avoid NULL dereference in CHAP auth error path

From: David Disseldorp <ddiss@suse.de>

commit ce512d79d0466a604793addb6b769d12ee326822 upstream.

If chap_server_compute_md5() fails early, e.g. via CHAP_N mismatch, then
crypto_free_shash() is called with a NULL pointer which gets
dereferenced in crypto_shash_tfm().

Fixes: 69110e3cedbb ("iscsi-target: Use shash and ahash")
Suggested-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: David Disseldorp <ddiss@suse.de>
Cc: stable@vger.kernel.org # 4.6+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/target/iscsi/iscsi_target_auth.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/target/iscsi/iscsi_target_auth.c
+++ b/drivers/target/iscsi/iscsi_target_auth.c
@@ -421,7 +421,8 @@ static int chap_server_compute_md5(
 	auth_ret = 0;
 out:
 	kzfree(desc);
-	crypto_free_shash(tfm);
+	if (tfm)
+		crypto_free_shash(tfm);
 	kfree(challenge);
 	kfree(challenge_binhex);
 	return auth_ret;


Patches currently in stable-queue which might be from ddiss@suse.de are

queue-4.15/target-iscsi-avoid-null-dereference-in-chap-auth-error-path.patch