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>
Signed-off-by: David S. Miller <davem@davemloft.net>
if (mdp->cd->shift_rd0)
desc_status >>= 16;
+ skb = mdp->rx_skbuff[entry];
if (desc_status & (RD_RFS1 | RD_RFS2 | RD_RFS3 | RD_RFS4 |
RD_RFS5 | RD_RFS6 | RD_RFS10)) {
ndev->stats.rx_errors++;
ndev->stats.rx_missed_errors++;
if (desc_status & RD_RFS10)
ndev->stats.rx_over_errors++;
- } else {
+ } else if (skb) {
if (!mdp->cd->hw_swap)
sh_eth_soft_swap(
phys_to_virt(ALIGN(rxdesc->addr, 4)),
pkt_len + 2);
- skb = mdp->rx_skbuff[entry];
mdp->rx_skbuff[entry] = NULL;
if (mdp->cd->rpadir)
skb_reserve(skb, NET_IP_ALIGN);