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i825xx: fix paging fault on znet_probe()

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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@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wu Fengguang 2012-09-01 21:25:46 +00:00 committed by David S. Miller
parent 3b59df46a4
commit b320e97240
1 changed files with 9 additions and 4 deletions
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13
drivers/net/ethernet/i825xx/znet.c
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@ -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;