From: Christian Lamparter chunkeey@gmail.com
commit 1645ab931998b39aed5761f095956f0b10a6362f upstream.
This patch fixes a crash that got introduced when the mentioned patch replaced the direct list_head access with skb_peek_tail(). When the device is starting up, there are no entries in the queue, so previously to "Use skb_peek_tail() instead..." the target_skb would end up as the tail and head pointer which then could be used by __skb_queue_after to fill the empty queue.
With skb_peek_tail() in its place will instead just return NULL which then causes a crash in the __skb_queue_after().
| BUG: unable to handle kernel NULL pointer dereference at 000000 | #PF error: [normal kernel read fault] | PGD 0 P4D 0 | Oops: 0000 [#1] SMP PTI | CPU: 0 PID: 12 Comm: kworker/0:1 Tainted: GO 5.1.0-rc7-wt+ #218 | Hardware name: MSI MS-7816/Z87-G43 (MS-7816), BIOS V1.11 05/09/2015 | Workqueue: events request_firmware_work_func | RIP: 0010:p54_tx_pending+0x10f/0x1b0 [p54common] | Code: 78 06 80 78 28 00 74 6d <48> 8b 07 49 89 7c 24 08 49 89 04 24 4 | RSP: 0018:ffffa81c81927d90 EFLAGS: 00010086 | RAX: ffff9bbaaf131048 RBX: 0000000000020670 RCX: 0000000000020264 | RDX: ffff9bbaa976d660 RSI: 0000000000000202 RDI: 0000000000000000 | RBP: ffff9bbaa976d620 R08: 00000000000006c0 R09: ffff9bbaa976d660 | R10: 0000000000000000 R11: ffffe8480dbc5900 R12: ffff9bbb45e87700 | R13: ffff9bbaa976d648 R14: ffff9bbaa976d674 R15: ffff9bbaaf131048 | FS: 0000000000000000(0000) GS:ffff9bbb5ec00000(0000) knlGS:00000 | CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 | CR2: 0000000000000000 CR3: 00000003695fc003 CR4: 00000000001606f0 | Call Trace: | p54_download_eeprom+0xbe/0x120 [p54common] | p54_read_eeprom+0x7f/0xc0 [p54common] | p54u_load_firmware_cb+0xe0/0x160 [p54usb] | request_firmware_work_func+0x42/0x80 | process_one_work+0x1f5/0x3f0 | worker_thread+0x28/0x3c0
Cc: stable@vger.kernel.org Fixes: e3554197fc8f ("p54: Use skb_peek_tail() instead of direct head pointer accesses.") Signed-off-by: Christian Lamparter chunkeey@gmail.com Signed-off-by: Kalle Valo kvalo@codeaurora.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/net/wireless/intersil/p54/txrx.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/net/wireless/intersil/p54/txrx.c +++ b/drivers/net/wireless/intersil/p54/txrx.c @@ -142,7 +142,10 @@ static int p54_assign_address(struct p54 unlikely(GET_HW_QUEUE(skb) == P54_QUEUE_BEACON)) priv->beacon_req_id = data->req_id;
- __skb_queue_after(&priv->tx_queue, target_skb, skb); + if (target_skb) + __skb_queue_after(&priv->tx_queue, target_skb, skb); + else + __skb_queue_head(&priv->tx_queue, skb); spin_unlock_irqrestore(&priv->tx_queue.lock, flags); return 0; }