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drm/vboxvideo: Replace fake VLA at end of vbva_mouse_pointer_shape with real VLA

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[ Upstream commit d92b90f9a54d9300a6e883258e79f36dab53bfae ]

Replace the fake VLA at end of the vbva_mouse_pointer_shape shape with
a real VLA to fix a "memcpy: detected field-spanning write error" warning:

[   13.319813] memcpy: detected field-spanning write (size 16896) of single field "p->data" at drivers/gpu/drm/vboxvideo/hgsmi_base.c:154 (size 4)
[   13.319841] WARNING: CPU: 0 PID: 1105 at drivers/gpu/drm/vboxvideo/hgsmi_base.c:154 hgsmi_update_pointer_shape+0x192/0x1c0 [vboxvideo]
[   13.320038] Call Trace:
[   13.320173]  hgsmi_update_pointer_shape [vboxvideo]
[   13.320184]  vbox_cursor_atomic_update [vboxvideo]

Note as mentioned in the added comment it seems the original length
calculation for the allocated and send hgsmi buffer is 4 bytes too large.
Changing this is not the goal of this patch, so this behavior is kept.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240827104523.17442-1-hdegoede@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Hans de Goede 2024-08-27 12:45:23 +02:00 committed by Greg Kroah-Hartman
parent 3dfd727873
commit 7458a6cdae
2 changed files with 10 additions and 4 deletions
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10
drivers/gpu/drm/vboxvideo/hgsmi_base.c
View File

@ -139,7 +139,15 @@ int hgsmi_update_pointer_shape(struct gen_pool *ctx, u32 flags,
flags |= VBOX_MOUSE_POINTER_VISIBLE;
}
p = hgsmi_buffer_alloc(ctx, sizeof(*p) + pixel_len, HGSMI_CH_VBVA,
/*
* The 4 extra bytes come from switching struct vbva_mouse_pointer_shape
* from having a 4 bytes fixed array at the end to using a proper VLA
* at the end. These 4 extra bytes were not subtracted from sizeof(*p)
* before the switch to the VLA, so this way the behavior is unchanged.
* Chances are these 4 extra bytes are not necessary but they are kept
* to avoid regressions.
*/
p = hgsmi_buffer_alloc(ctx, sizeof(*p) + pixel_len + 4, HGSMI_CH_VBVA,
VBVA_MOUSE_POINTER_SHAPE);
if (!p)
return -ENOMEM;

4
drivers/gpu/drm/vboxvideo/vboxvideo.h
View File

@ -351,10 +351,8 @@ struct vbva_mouse_pointer_shape {
* Bytes in the gap between the AND and the XOR mask are undefined.
* XOR mask scanlines have no gap between them and size of XOR mask is:
* xor_len = width * 4 * height.
*
* Preallocate 4 bytes for accessing actual data as p->data.
*/
u8 data[4];
u8 data[];
} __packed;
/* pointer is visible */