| Message ID | 4859772.ltR2e4ZqZH@wasted.cogentembedded.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Geert Uytterhoeven |
| Headers | show |
Hello. On 10/24/2015 2:09 AM, Sergei Shtylyov 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 <yashi@atmark-techno.com> > Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> > > --- > This patch is against DaveM's 'net.git' repo. > > drivers/net/ethernet/renesas/sh_eth.c | 3 +++ > 1 file changed, 3 insertions(+) > > Index: net/drivers/net/ethernet/renesas/sh_eth.c > =================================================================== > --- net.orig/drivers/net/ethernet/renesas/sh_eth.c > +++ net/drivers/net/ethernet/renesas/sh_eth.c > @@ -1502,6 +1502,8 @@ static int sh_eth_rx(struct net_device * > phys_to_virt(ALIGN(rxdesc->addr, 4)), > pkt_len + 2); > skb = mdp->rx_skbuff[entry]; > + if (!skb) > + goto skip; > mdp->rx_skbuff[entry] = NULL; > if (mdp->cd->rpadir) > skb_reserve(skb, NET_IP_ALIGN); > @@ -1516,6 +1518,7 @@ static int sh_eth_rx(struct net_device * > if (desc_status & RD_RFS8) > ndev->stats.multicast++; > } > +skip: > entry = (++mdp->cur_rx) % mdp->num_rx_ring; > rxdesc = &mdp->rx_ring[entry]; > } In fact, it could be done without goto/label. I'll recast. MBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Index: net/drivers/net/ethernet/renesas/sh_eth.c =================================================================== --- net.orig/drivers/net/ethernet/renesas/sh_eth.c +++ net/drivers/net/ethernet/renesas/sh_eth.c @@ -1502,6 +1502,8 @@ static int sh_eth_rx(struct net_device * phys_to_virt(ALIGN(rxdesc->addr, 4)), pkt_len + 2); skb = mdp->rx_skbuff[entry]; + if (!skb) + goto skip; mdp->rx_skbuff[entry] = NULL; if (mdp->cd->rpadir) skb_reserve(skb, NET_IP_ALIGN); @@ -1516,6 +1518,7 @@ static int sh_eth_rx(struct net_device * if (desc_status & RD_RFS8) ndev->stats.multicast++; } +skip: entry = (++mdp->cur_rx) % mdp->num_rx_ring; rxdesc = &mdp->rx_ring[entry]; }
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 <yashi@atmark-techno.com> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> --- This patch is against DaveM's 'net.git' repo. drivers/net/ethernet/renesas/sh_eth.c | 3 +++ 1 file changed, 3 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html