From 7ba1b689038726d34e3244c1ac9e2e18c2ea4787 Mon Sep 17 00:00:00 2001 From: Ralf Baechle Date: Thu, 9 Feb 2017 14:12:11 +0100 Subject: [PATCH] NET: mkiss: Fix panic If a USB-to-serial adapter is unplugged, the driver re-initializes, with dev->hard_header_len and dev->addr_len set to zero, instead of the correct values. If then a packet is sent through the half-dead interface, the kernel will panic due to running out of headroom in the skb when pushing for the AX.25 headers resulting in this panic: [] (skb_panic) from [] (skb_push+0x4c/0x50) [] (skb_push) from [] (ax25_hard_header+0x34/0xf4 [ax25]) [] (ax25_hard_header [ax25]) from [] (ax_header+0x38/0x40 [mkiss]) [] (ax_header [mkiss]) from [] (neigh_compat_output+0x8c/0xd8) [] (neigh_compat_output) from [] (ip_finish_output+0x2a0/0x914) [] (ip_finish_output) from [] (ip_output+0xd8/0xf0) [] (ip_output) from [] (ip_local_out_sk+0x44/0x48) This patch makes mkiss behave like the 6pack driver. 6pack does not panic. In 6pack.c sp_setup() (same function name here) the values for dev->hard_header_len and dev->addr_len are set to the same values as in my mkiss patch. [ralf@linux-mips.org: Massages original submission to conform to the usual standards for patch submissions.] Signed-off-by: Thomas Osterried Signed-off-by: Ralf Baechle Signed-off-by: David S. Miller --- drivers/net/hamradio/mkiss.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c index ece59c54a653..4a40a3d825b4 100644 --- a/drivers/net/hamradio/mkiss.c +++ b/drivers/net/hamradio/mkiss.c @@ -648,8 +648,8 @@ static void ax_setup(struct net_device *dev) { /* Finish setting up the DEVICE info. */ dev->mtu = AX_MTU; - dev->hard_header_len = 0; - dev->addr_len = 0; + dev->hard_header_len = AX25_MAX_HEADER_LEN; + dev->addr_len = AX25_ADDR_LEN; dev->type = ARPHRD_AX25; dev->tx_queue_len = 10; dev->header_ops = &ax25_header_ops; -- 2.30.2