From: Luigi Leonardi <leonardi@redhat.com>
To: Tommaso Califano <tcalifano@redhat.com>
Cc: qemu-devel@nongnu.org,
"Philippe Mathieu-Daudé" <philmd@oss.qualcomm.com>,
"Paolo Bonzini" <pbonzini@redhat.com>
Subject: Re: [PATCH v2] hw/usb/dev-mtp: Fix assert crash on short CMD_SEND_OBJECT
Date: Thu, 8 Oct 2026 14:38:23 +0200 [thread overview]
Message-ID: <aseOsAfB3GuyghJF@leonardi-redhat> (raw)
In-Reply-To: <20261008122936.45081-1-tcalifano@redhat.com>
On Thu, Oct 08, 2026 at 02:29:36PM +0200, Tommaso Califano wrote:
>In usb_mtp_get_data() there is a guest-triggerable assertion that fires
>when a guest declares a large object size in CMD_SEND_OBJECT_INFO but
>sends fewer bytes in the subsequent CMD_SEND_OBJECT. The assertion
>compares the declared size against the actual bytes received.
>
>If the guest sends CMD_SEND_OBJECT_INFO with size=1000 and then
>CMD_SEND_OBJECT with only 50 bytes (short, non-64-byte-aligned
>final USB packet) the assertion fires, killing QEMU.
>
>To prevent that is sufficient to remove the assertion, because the case
>is handled by usb_mtp_write_data() which returns RES_INCOMPLETE_TRANSFER.
>
>Fixes: 3e096650a64d ("dev-mtp: Add support for > 4GB file transfers")
>Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3993
>Signed-off-by: Tommaso Califano <tcalifano@redhat.com>
Reviewed-by: Luigi Leonardi <leonardi@redhat.com>
next prev parent reply other threads:[~2026-10-08 12:38 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-08 12:29 [PATCH v2] hw/usb/dev-mtp: Fix assert crash on short CMD_SEND_OBJECT Tommaso Califano
2026-10-08 12:35 ` Marc-André Lureau
2026-10-08 12:38 ` Luigi Leonardi [this message]
2026-10-08 20:45 ` Philippe Mathieu-Daudé
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