On 7/11/25 15:39, Peter Maydell wrote:
In fimd_update_memory_section() we attempt ot find and map part of
the RAM MR which backs the framebuffer, based on guest-configurable
size and start address.
If the guest configures framebuffer settings which result in a
zero-sized framebuffer, we hit an assertion(), because
memory_region_find() will return a NULL mem_section.mr.
The datasheet is not clear about what to do here...
41.3.10 Virtual Display
The size of video buffer in which you store the image should
be larger than the LCD panel screen size.
OFFSIZE_F should have value that is multiple of 4byte size or 0.
PAGEWIDTH should have bigger value than the burst size and you
should align the size word boundary.
(virtpage_offsize is OFFSIZE_F and virtpage_width is PAGEWIDTH).
I couldn't find any info more useful, and your patch is safe, so:
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Explicitly check for the zero-size case and treat this as a
guest error.
Because we now have a code path which can reach error_return without
calling memory_region_find to set w->mem_section, we must NULL out
w->mem_section.mr after the unref of the old MR, so that error_return
does not incorrectly double-unref the old MR.
Cc: [email protected]
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1407
Signed-off-by: Peter Maydell <[email protected]>
---
hw/display/exynos4210_fimd.c | 7 +++++++
1 file changed, 7 insertions(+)
