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Subject: media: v4l2-compat-ioctl32: Fix timespec conversion
Author:  Daniel Mentz <>
Date:    Wed Aug 2 23:42:17 2017 -0400

Certain syscalls like recvmmsg support 64 bit timespec values for the
X32 ABI. The helper function compat_put_timespec converts a timespec
value to a 32 bit or 64 bit value depending on what ABI is used. The
v4l2 compat layer, however, is not designed to support 64 bit timespec
values and always uses 32 bit values. Hence, compat_put_timespec must
not be used.

Without this patch, user space will be provided with bad timestamp
values from the VIDIOC_DQEVENT ioctl. Also, fields of the struct
v4l2_event32 that come immediately after timestamp get overwritten,
namely the field named id.

Fixes: 81993e81a994 ("compat: Get rid of (get|put)_compat_time(val|spec)")

Cc: H. Peter Anvin <>
Cc: Laurent Pinchart <>
Cc: Tiffany Lin <>
Cc: Ricardo Ribalda Delgado <>
Cc: Sakari Ailus <>
Signed-off-by: Daniel Mentz <>
Signed-off-by: Hans Verkuil <>
Signed-off-by: Mauro Carvalho Chehab <>

 drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)


diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c 
index 84ad195562c7..af8b4c5b0efa 100644
--- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
+++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
@@ -799,7 +799,8 @@ static int put_v4l2_event32(struct v4l2_event *kp, struct 
v4l2_event32 __user *u
                copy_to_user(&up->u, &kp->u, sizeof(kp->u)) ||
                put_user(kp->pending, &up->pending) ||
                put_user(kp->sequence, &up->sequence) ||
-               compat_put_timespec(&kp->timestamp, &up->timestamp) ||
+               put_user(kp->timestamp.tv_sec, &up->timestamp.tv_sec) ||
+               put_user(kp->timestamp.tv_nsec, &up->timestamp.tv_nsec) ||
                put_user(kp->id, &up->id) ||
                copy_to_user(up->reserved, kp->reserved, 8 * sizeof(__u32)))
                        return -EFAULT;

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