From a8e93f3dccc066cd6dd1e9db1e35942914fc57d1 Mon Sep 17 00:00:00 2001 From: Clemens Ladisch <clemens@ladisch.de> Date: Wed, 7 Jul 2010 14:37:30 +0200 Subject: [PATCH] firewire: cdev: check write quadlet request length to avoid buffer overflow Check that the data length of a write quadlet request actually is large enough for a quadlet. Otherwise, fw_fill_request could access the four bytes after the end of the outbound_transaction_event structure. Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Modification of Clemens' change: Consolidate the check into init_request() which is used by the affected ioctl_send_request() and ioctl_send_broadcast_request() and the unaffected ioctl_send_stream_packet(), to save a few lines of code. Note, since struct outbound_transaction_event *e is slab-allocated, such an out-of-bounds access won't hit unallocated memory but may result in a (virtually impossible to exploit) information disclosure. Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> --- drivers/firewire/core-cdev.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c index d8ac0ce2d6bf..f7559bfeaba3 100644 --- a/drivers/firewire/core-cdev.c +++ b/drivers/firewire/core-cdev.c @@ -563,6 +563,10 @@ static int init_request(struct client *client, (request->length > 4096 || request->length > 512 << speed)) return -EIO; + if (request->tcode == TCODE_WRITE_QUADLET_REQUEST && + request->length < 4) + return -EINVAL; + e = kmalloc(sizeof(*e) + request->length, GFP_KERNEL); if (e == NULL) return -ENOMEM; -- GitLab