Re: [PATCH 1/1] r8152: fix NULL pointer dereference in r8152_poll
From: Eric Dumazet <hidden>
Date: 2017-03-13 13:18:06
On Mon, 2017-03-13 at 13:47 +0100, Petr Vorel wrote:
quoted hunk ↗ jump to hunk
commit 7489bdadb7d1 (r8152: check rx after napi is enabled) causes null pointer dereference when using device as under root: # rmmod r8152 # or lsusb -v NOHZ: local_softirq_pending 08 BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: r8152_poll+0x125/0x570 [r8152] PGD 89b4cf067 PUD 898ff2067 PMD 0 Oops: 0002 [#1] PREEMPT SMP Signed-off-by: Petr Vorel <redacted> --- NOTE: This is just a workaround, I suppose, there is better way how to fix that (which allows keeping scheduling the napi for rx after napi_enable()). --- drivers/net/usb/r8152.c | 2 -- 1 file changed, 2 deletions(-)diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c index 986243c932cc..79c665a89a47 100644 --- a/drivers/net/usb/r8152.c +++ b/drivers/net/usb/r8152.c@@ -3703,8 +3703,6 @@ static int rtl8152_resume(struct usb_interface *intf) napi_enable(&tp->napi); clear_bit(SELECTIVE_SUSPEND, &tp->flags); smp_mb__after_atomic(); - if (!list_empty(&tp->rx_done)) - napi_schedule(&tp->napi); } else { tp->rtl_ops.up(tp); netif_carrier_off(tp->netdev);
The proper work around is to enclose the napi_schedule() in a local_bh_enable()/local_bh_disable() pair.