From 448d7b5daf043d109df98e3e8f8deb165c2e8896 Mon Sep 17 00:00:00 2001 From: Nelson Elhage Date: Thu, 28 Oct 2010 11:31:07 -0700 Subject: pktgen: Limit how much data we copy onto the stack. A program that accidentally writes too much data to the pktgen file can overflow the kernel stack and oops the machine. This is only triggerable by root, so there's no security issue, but it's still an unfortunate bug. printk() won't print more than 1024 bytes in a single call, anyways, so let's just never copy more than that much data. We're on a fairly shallow stack, so that should be safe even with CONFIG_4KSTACKS. Signed-off-by: Nelson Elhage Signed-off-by: David S. Miller --- net/core/pktgen.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'net/core') diff --git a/net/core/pktgen.c b/net/core/pktgen.c index 679b797d06b..fbce4b05a53 100644 --- a/net/core/pktgen.c +++ b/net/core/pktgen.c @@ -887,10 +887,11 @@ static ssize_t pktgen_if_write(struct file *file, i += len; if (debug) { - char tb[count + 1]; - if (copy_from_user(tb, user_buffer, count)) + size_t copy = min(count, 1023); + char tb[copy + 1]; + if (copy_from_user(tb, user_buffer, copy)) return -EFAULT; - tb[count] = 0; + tb[copy] = 0; printk(KERN_DEBUG "pktgen: %s,%lu buffer -:%s:-\n", name, (unsigned long)count, tb); } -- cgit v1.2.3-70-g09d2