This is a note to let you know that I've just added the patch titled
misc: mic: fix possible signed underflow (undefined behavior) in
to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 3b1cc9b9622a022208ec95b1259b05bbdf712eb7 Mon Sep 17 00:00:00 2001
From: Sudeep Dutt <sudeep.dutt@xxxxxxxxx>
Date: Mon, 3 Feb 2014 14:53:19 -0800
Subject: 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 <mathieu.desnoyers@xxxxxxxxxxxx>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@xxxxxxxxx>
Signed-off-by: Sudeep Dutt <sudeep.dutt@xxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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 752ff873f891..7e1ef0ebbb80 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 7fabba5059cf..feb0b4c0814c 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;
--
1.8.5.1.163.gd7aced9
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