From 3b1cc9b9622a022208ec95b1259b05bbdf712eb7 Mon Sep 17 00:00:00 2001 From: Sudeep Dutt Date: Mon, 3 Feb 2014 14:53:19 -0800 Subject: [PATCH] misc: mic: fix possible signed underflow (undefined behavior) in userspace API iovcnt is declared as a signed integer in both the userspace API and as a local variable in mic_virtio.c. The while() loop in mic_virtio.c iterates until the local variable iovcnt reaches the value 0. If userspace passes e.g. INT_MIN as iovcnt field, this loop then appears to depend on an undefined behavior (signed underflow) to complete. The fix is to use unsigned integers in both the userspace API and the local variable. This issue was reported @ https://lkml.org/lkml/2014/1/10/10 Reported-by: Mathieu Desnoyers Reviewed-by: Ashutosh Dixit Signed-off-by: Sudeep Dutt Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/misc/mic/host/mic_virtio.c | 3 ++- include/uapi/linux/mic_ioctl.h | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/misc/mic/host/mic_virtio.c b/drivers/misc/mic/host/mic_virtio.c index 752ff87..7e1ef0e 100644 --- a/drivers/misc/mic/host/mic_virtio.c +++ b/drivers/misc/mic/host/mic_virtio.c @@ -156,7 +156,8 @@ static int mic_vringh_copy(struct mic_vdev *mvdev, struct vringh_kiov *iov, static int _mic_virtio_copy(struct mic_vdev *mvdev, struct mic_copy_desc *copy) { - int ret = 0, iovcnt = copy->iovcnt; + int ret = 0; + u32 iovcnt = copy->iovcnt; struct iovec iov; struct iovec __user *u_iov = copy->iov; void __user *ubuf = NULL; diff --git a/include/uapi/linux/mic_ioctl.h b/include/uapi/linux/mic_ioctl.h index 7fabba5..feb0b4c 100644 --- a/include/uapi/linux/mic_ioctl.h +++ b/include/uapi/linux/mic_ioctl.h @@ -39,7 +39,7 @@ struct mic_copy_desc { #else struct iovec *iov; #endif - int iovcnt; + __u32 iovcnt; __u8 vr_idx; __u8 update_used; __u32 out_len; -- 2.7.4