Re: [syzbot] Test for 2ef3a8ce8e91b5a50098

[syzbot <syzbot+2ef3a8ce8e91b5a50098@syzkaller.appspotmail.com>]

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Subject: Test for 2ef3a8ce8e91b5a50098
Author: syoshida@redhat.com

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 9f8413c4a66f2fb776d3dc3c9ed20bf435eb305e

diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
index 6d14d935ee82..b983232e25cb 100644
--- a/net/hsr/hsr_framereg.c
+++ b/net/hsr/hsr_framereg.c
@@ -228,6 +228,9 @@ struct hsr_node *hsr_get_node(struct hsr_port *port, struct list_head *node_db,
 	 */
 	if (ethhdr->h_proto == htons(ETH_P_PRP) ||
 	    ethhdr->h_proto == htons(ETH_P_HSR)) {
+		if (skb->mac_len < sizeof(struct hsr_ethhdr))
+			return NULL;
+
 		/* Use the existing sequence_nr from the tag as starting point
 		 * for filtering duplicate frames.
 		 */