Patch "sh_eth: fix kernel oops in skb_put()" has been added to the 3.10-stable tree

This is a note to let you know that I've just added the patch titled

sh_eth: fix kernel oops in skb_put()

to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
sh_eth-fix-kernel-oops-in-skb_put.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Sergei Shtylyov <[email protected]>
Date: Fri, 4 Dec 2015 01:45:40 +0300
Subject: sh_eth: fix kernel oops in skb_put()
Status: RO
Content-Length: 2307
Lines: 61

From: Sergei Shtylyov <[email protected]>

[ Upstream commit 248be83dcb3feb3f6332eb3d010a016402138484 ]

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...

---
 drivers/net/ethernet/renesas/sh_eth.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -1421,6 +1421,7 @@ static int sh_eth_rx(struct net_device *
 		desc_status >>= 16;
 #endif
 
+		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++;

@@ -1436,12 +1437,11 @@ static int sh_eth_rx(struct net_device *
 				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);

Patches currently in stable-queue which might be from [email protected] are

queue-3.10/sh_eth-fix-kernel-oops-in-skb_put.patch