[patch v2] fix stack overflow in pktgen_if_write()
From: Dan Carpenter <hidden>
Date: 2010-10-27 22:43:16
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Nelson Elhage says he was able to oops both amd64 and i386 test machines with 8k writes to the pktgen file. Let's just allocate the buffer on the heap instead of on the stack. This can only be triggered by root so there are no security issues here. Reported-by: Nelson Elhage <redacted> Signed-off-by: Dan Carpenter <redacted> --- I saw this on twitter. Hi Nelson, could you test this? V2: strndup_user() => memdup_user()
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 2c0df0f..b5d3c70 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c@@ -887,12 +887,14 @@ 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)) - return -EFAULT; - tb[count] = 0; + char *tb; + + tb = memdup_user(user_buffer, count + 1); + if (IS_ERR(tb)) + return PTR_ERR(tb); printk(KERN_DEBUG "pktgen: %s,%lu buffer -:%s:-\n", name, (unsigned long)count, tb); + kfree(tb); } if (!strcmp(name, "min_pkt_size")) {