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Message-ID: <20120902072546.GA20290@localhost>
Date: Sun, 2 Sep 2012 15:25:46 +0800
From: Fengguang Wu <fengguang.wu@...el.com>
To: David Miller <davem@...emloft.net>
Cc: Jeff Kirsher <jeffrey.t.kirsher@...el.com>, netdev@...r.kernel.org,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] i825xx: fix paging fault on znet_probe()
In znet_probe(), strncmp() may access beyond 0x100000 and
trigger the below oops in kvm. Fix it by limiting the loop
under 0x100000-8. I suspect the limit could be further decreased
to 0x100000-sizeof(struct netidblk), however no datasheet at hand..
[ 3.744312] BUG: unable to handle kernel paging request at 80100000
[ 3.746145] IP: [<8119d12a>] strncmp+0xc/0x20
[ 3.747446] *pde = 01d10067 *pte = 00100160
[ 3.747493] Oops: 0000 [#1] DEBUG_PAGEALLOC
[ 3.747493] Pid: 1, comm: swapper Not tainted 3.6.0-rc1-00018-g57bfc0a #73 Bochs Bochs
[ 3.747493] EIP: 0060:[<8119d12a>] EFLAGS: 00010206 CPU: 0
[ 3.747493] EIP is at strncmp+0xc/0x20
[ 3.747493] EAX: 800fff4e EBX: 00000006 ECX: 00000006 EDX: 814d2bb9
[ 3.747493] ESI: 80100000 EDI: 814d2bba EBP: 8e03dfa0 ESP: 8e03df98
[ 3.747493] DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068
[ 3.747493] CR0: 8005003b CR2: 80100000 CR3: 016f7000 CR4: 00000690
[ 3.747493] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[ 3.747493] DR6: ffff0ff0 DR7: 00000400
[ 3.747493] Process swapper (pid: 1, ti=8e03c000 task=8e040000 task.ti=8e03c000)
[ 3.747493] Stack:
[ 3.747493] 800fffff 00000000 8e03dfb4 816a1376 00000006 816a134a 00000000 8e03dfd0
[ 3.747493] 816819b5 816ed1c0 8e03dfe4 00000006 00000123 816ed604 8e03dfe4 81681b29
[ 3.747493] 00000000 81681a5b 00000000 00000000 8134e542 00000000 00000000 00000000
[ 3.747493] Call Trace:
[ 3.747493] [<816a1376>] znet_probe+0x2c/0x26b
[ 3.747493] [<816a134a>] ? dnet_driver_init+0xf/0xf
[ 3.747493] [<816819b5>] do_one_initcall+0x6a/0x110
[ 3.747493] [<81681b29>] kernel_init+0xce/0x14b
Signed-off-by: Fengguang Wu <fengguang.wu@...el.com>
---
drivers/net/ethernet/i825xx/znet.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- linux.orig/drivers/net/ethernet/i825xx/znet.c 2012-05-24 19:03:06.928430941 +0800
+++ linux/drivers/net/ethernet/i825xx/znet.c 2012-09-02 15:14:24.943249546 +0800
@@ -139,8 +139,11 @@ struct znet_private {
/* Only one can be built-in;-> */
static struct net_device *znet_dev;
+#define NETIDBLK_MAGIC "NETIDBLK"
+#define NETIDBLK_MAGIC_SIZE 8
+
struct netidblk {
- char magic[8]; /* The magic number (string) "NETIDBLK" */
+ char magic[NETIDBLK_MAGIC_SIZE]; /* The magic number (string) "NETIDBLK" */
unsigned char netid[8]; /* The physical station address */
char nettype, globalopt;
char vendor[8]; /* The machine vendor and product name. */
@@ -373,14 +376,16 @@ static int __init znet_probe (void)
struct znet_private *znet;
struct net_device *dev;
char *p;
+ char *plast = phys_to_virt(0x100000 - NETIDBLK_MAGIC_SIZE);
int err = -ENOMEM;
/* This code scans the region 0xf0000 to 0xfffff for a "NETIDBLK". */
- for(p = (char *)phys_to_virt(0xf0000); p < (char *)phys_to_virt(0x100000); p++)
- if (*p == 'N' && strncmp(p, "NETIDBLK", 8) == 0)
+ for(p = (char *)phys_to_virt(0xf0000); p <= plast; p++)
+ if (*p == 'N' &&
+ strncmp(p, NETIDBLK_MAGIC, NETIDBLK_MAGIC_SIZE) == 0)
break;
- if (p >= (char *)phys_to_virt(0x100000)) {
+ if (p > plast) {
if (znet_debug > 1)
printk(KERN_INFO "No Z-Note ethernet adaptor found.\n");
return -ENODEV;
--
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