From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Date: Sat, 05 Dec 2015 22:46:48 +0000 Subject: Re: [PATCH v3] sh_eth: fix kernel oops in skb_put() Message-Id: <20151205.174648.1064779484509050839.davem@davemloft.net> List-Id: References: <1498048.4g9dLWgJuk@wasted.cogentembedded.com> In-Reply-To: <1498048.4g9dLWgJuk@wasted.cogentembedded.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: sergei.shtylyov@cogentembedded.com Cc: netdev@vger.kernel.org, yashi@atmark-techno.com, linux-sh@vger.kernel.org From: Sergei Shtylyov Date: Fri, 04 Dec 2015 01:45:40 +0300 > In a low memory situation the following kernel oops occurs: > > Unable to handle kernel NULL pointer dereference at virtual address 00000050 > pgd = 8490c000 > [00000050] *pgdF51e831, *pte000000, *ppte000000 > 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 > Signed-off-by: Sergei Shtylyov Applied.