Subject: Re: [PATCH v3] sh_eth: fix kernel oops in skb_put()

From: Sergei Shtylyov <[email-masked]>
Date: Sat, 12 Dec 2015 18:17:45 +0300

Hello.

On 12/6/2015 1:46 AM, David Miller wrote:

>> In a low memory situation the following kernel oops occurs:
>>
>> Unable to handle kernel NULL pointer dereference at virtual address 00000050
>> pgd = 8490c000
>> [00000050] *pgd=4651e831, *pte=00000000, *ppte=00000000
>> Internal error: Oops: 17 [#1] PREEMPT ARM
>> Modules linked in:
>> CPU: 0    Not tainted  (3.4-at16 #9)
>> PC is at skb_put+0x10/0x98
>> LR is at sh_eth_poll+0x2c8/0xa10
>> pc : [<8035f780>]    lr : [<8028bf50>]    psr: 60000113
>> sp : 84eb1a90  ip : 84eb1ac8  fp : 84eb1ac4
>> r10: 0000003f  r9 : 000005ea  r8 : 00000000
>> r7 : 00000000  r6 : 940453b0  r5 : 00030000  r4 : 9381b180
>> r3 : 00000000  r2 : 00000000  r1 : 000005ea  r0 : 00000000
>> Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
>> Control: 10c53c7d  Table: 4248c059  DAC: 00000015
>> Process klogd (pid: 2046, stack limit = 0x84eb02e8)
>> [...]
>>
>> This is  because netdev_alloc_skb() fails and 'mdp->rx_skbuff[entry]' is left
>> NULL but sh_eth_rx() later  uses it without checking.  Add such check...
>>
>> Reported-by: Yasushi SHOJI <[email-masked]>
>> Signed-off-by: Sergei Shtylyov <[email-masked]>

> Applied.

    Could you also queue this for the stable kernels?

MBR, Sergei