Patch "media: uvcvideo: Enforce alignment of frame and interval" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    media: uvcvideo: Enforce alignment of frame and interval

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     media-uvcvideo-enforce-alignment-of-frame-and-interv.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 7894235bff04bbd5322bc91eb7c6338ed7546592
Author: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
Date:   Thu Apr 4 17:56:18 2024 +0000

    media: uvcvideo: Enforce alignment of frame and interval
    
    [ Upstream commit c8931ef55bd325052ec496f242aea7f6de47dc9c ]
    
    Struct uvc_frame and interval (u32*) are packaged together on
    streaming->formats on a single contiguous allocation.
    
    Right now they are allocated right after uvc_format, without taking into
    consideration their required alignment.
    
    This is working fine because both structures have a field with a
    pointer, but it will stop working when the sizeof() of any of those
    structs is not a multiple of the sizeof(void*).
    
    Enforce that alignment during the allocation.
    
    Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
    Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240404-uvc-align-v2-1-9e104b0ecfbd@xxxxxxxxxxxx
    Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 0caa57a6782a..6d1a7e02da51 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -887,16 +887,26 @@ static int uvc_parse_streaming(struct uvc_device *dev,
 		goto error;
 	}
 
-	size = nformats * sizeof(*format) + nframes * sizeof(*frame)
+	/*
+	 * Allocate memory for the formats, the frames and the intervals,
+	 * plus any required padding to guarantee that everything has the
+	 * correct alignment.
+	 */
+	size = nformats * sizeof(*format);
+	size = ALIGN(size, __alignof__(*frame)) + nframes * sizeof(*frame);
+	size = ALIGN(size, __alignof__(*interval))
 	     + nintervals * sizeof(*interval);
+
 	format = kzalloc(size, GFP_KERNEL);
-	if (format == NULL) {
+	if (!format) {
 		ret = -ENOMEM;
 		goto error;
 	}
 
-	frame = (struct uvc_frame *)&format[nformats];
-	interval = (u32 *)&frame[nframes];
+	frame = (void *)format + nformats * sizeof(*format);
+	frame = PTR_ALIGN(frame, __alignof__(*frame));
+	interval = (void *)frame + nframes * sizeof(*frame);
+	interval = PTR_ALIGN(interval, __alignof__(*interval));
 
 	streaming->format = format;
 	streaming->nformats = nformats;