isdn: icn: Fix stack overflow bug
From: Steven Rostedt
Date: Tue Nov 23 2010 - 23:39:45 EST
Running randconfig with ktest.pl I hit this bug:
[ 16.101158] ICN-ISDN-driver Rev 1.65.6.8 mem=0x000d0000
[ 16.106376] icn: (line0) ICN-2B, port 0x320 added
[ 16.111064] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: c1642880
[ 16.111066]
[ 16.121214] Pid: 1, comm: swapper Not tainted 2.6.37-rc2-test-00124-g6656b3f #8
[ 16.128499] Call Trace:
[ 16.130942] [<c0f51662>] ? printk+0x1d/0x23
[ 16.135200] [<c0f5153f>] panic+0x5c/0x162
[ 16.139286] [<c0d62a9a>] ? icn_addcard+0x6d/0xbe
[ 16.143975] [<c0445783>] print_tainted+0x0/0x8c
[ 16.148582] [<c1642880>] ? icn_init+0xd8/0xdf
[ 16.153012] [<c1642880>] icn_init+0xd8/0xdf
[ 16.157271] [<c04012e5>] do_one_initcall+0x8c/0x143
[ 16.162222] [<c16427a8>] ? icn_init+0x0/0xdf
[ 16.166566] [<c15f1a05>] kernel_init+0x13f/0x1da
[ 16.171256] [<c15f18c6>] ? kernel_init+0x0/0x1da
[ 16.175945] [<c0403bfe>] kernel_thread_helper+0x6/0x10
[ 16.181181] panic occurred, switching back to text console
Looking into it I found that the stack was corrupted by the assignment
of the Rev #. The variable rev is given 10 bytes, and in this output the
characters that were copied was: " 1.65.6.8 $". Which was 11 characters
plus the null ending character for a total of 12 bytes, thus corrupting
the stack.
This patch ups the variable size to 20 bytes as well as changes the
strcpy to strncpy. I also added a check to make sure '$' is found.
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
diff --git a/drivers/isdn/icn/icn.c b/drivers/isdn/icn/icn.c
index 2e847a9..f2b5bab 100644
--- a/drivers/isdn/icn/icn.c
+++ b/drivers/isdn/icn/icn.c
@@ -1627,7 +1627,7 @@ __setup("icn=", icn_setup);
static int __init icn_init(void)
{
char *p;
- char rev[10];
+ char rev[20];
memset(&dev, 0, sizeof(icn_dev));
dev.memaddr = (membase & 0x0ffc000);
@@ -1637,9 +1637,10 @@ static int __init icn_init(void)
spin_lock_init(&dev.devlock);
if ((p = strchr(revision, ':'))) {
- strcpy(rev, p + 1);
+ strncpy(rev, p + 1, 20);
p = strchr(rev, '$');
- *p = 0;
+ if (p)
+ *p = 0;
} else
strcpy(rev, " ??? ");
printk(KERN_NOTICE "ICN-ISDN-driver Rev%smem=0x%08lx\n", rev,
--
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