* [PATCH] usb-storage: tag usb_msd_csw as packed struct
@ 2021-09-06 4:55 Gerd Hoffmann
2021-09-06 9:24 ` Philippe Mathieu-Daudé
0 siblings, 1 reply; 2+ messages in thread
From: Gerd Hoffmann @ 2021-09-06 4:55 UTC (permalink / raw)
To: qemu-devel; +Cc: vintagepc404, Gerd Hoffmann
Without this the struct has the wrong size: sizeof() evaluates
to 16 instead of 13. In most cases the bug is hidden by the
fact that guests submits a buffer which is exactly 13 bytes
long, so the padding added by the compiler is simply ignored.
But sometimes guests submit a larger buffer and expect a short
transfer, which does not work properly with the wrong struct
size.
Cc: vintagepc404@protonmail.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
include/hw/usb/msd.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/hw/usb/msd.h b/include/hw/usb/msd.h
index 7538c54569bf..54e9f38bda46 100644
--- a/include/hw/usb/msd.h
+++ b/include/hw/usb/msd.h
@@ -17,7 +17,7 @@ enum USBMSDMode {
USB_MSDM_CSW /* Command Status. */
};
-struct usb_msd_csw {
+struct QEMU_PACKED usb_msd_csw {
uint32_t sig;
uint32_t tag;
uint32_t residue;
--
2.31.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] usb-storage: tag usb_msd_csw as packed struct
2021-09-06 4:55 [PATCH] usb-storage: tag usb_msd_csw as packed struct Gerd Hoffmann
@ 2021-09-06 9:24 ` Philippe Mathieu-Daudé
0 siblings, 0 replies; 2+ messages in thread
From: Philippe Mathieu-Daudé @ 2021-09-06 9:24 UTC (permalink / raw)
To: Gerd Hoffmann, qemu-devel; +Cc: vintagepc404
On 9/6/21 6:55 AM, Gerd Hoffmann wrote:
> Without this the struct has the wrong size: sizeof() evaluates
> to 16 instead of 13. In most cases the bug is hidden by the
> fact that guests submits a buffer which is exactly 13 bytes
> long, so the padding added by the compiler is simply ignored.
>
> But sometimes guests submit a larger buffer and expect a short
> transfer, which does not work properly with the wrong struct
> size.
>
> Cc: vintagepc404@protonmail.com
Fixes: a917d384ac0 ("SCSI TCQ support.")
15 years old bug, nice =)
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
> include/hw/usb/msd.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-09-06 4:55 [PATCH] usb-storage: tag usb_msd_csw as packed struct Gerd Hoffmann
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