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authorNelson Elhage <nelhage@ksplice.com>2010-10-28 11:31:07 -0700
committerDavid S. Miller <davem@davemloft.net>2010-10-28 11:47:53 -0700
commit448d7b5daf043d109df98e3e8f8deb165c2e8896 (patch)
tree475844d92c01fae639bda19988ba1375272c857a
parent8acfe468b0384e834a303f08ebc4953d72fb690a (diff)
downloadlinux-2.6.38-lt-ux500-448d7b5daf043d109df98e3e8f8deb165c2e8896.tar.gz
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 <nelhage@ksplice.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/core/pktgen.c7
1 files changed, 4 insertions, 3 deletions
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);
}