From: Alexander Graf <agraf@suse.de>
To: P J P <ppandit@redhat.com>
Cc: Qemu Developers <qemu-devel@nongnu.org>,
Paolo Bonzini <pbonzini@redhat.com>, Li Qiang <liqiang6-s@360.cn>,
Hannes Reinecke <hare@suse.de>
Subject: Re: [Qemu-devel] [PATCH 1/3] scsi: megasas: use appropriate property buffer size
Date: Wed, 25 May 2016 13:53:31 +0200 [thread overview]
Message-ID: <5745923B.4060102@suse.de> (raw)
In-Reply-To: <alpine.LFD.2.20.1605251718250.15974@wniryva>
On 05/25/2016 01:51 PM, P J P wrote:
> Hello Alex,
>
> +-- On Wed, 25 May 2016, Alexander Graf wrote --+
> | > - dma_buf_write((uint8_t *)&info, cmd->iov_size, &cmd->qsg);
> | > + dma_buf_write((uint8_t *)&info, dcmd_size, &cmd->qsg);
> |
> | This looks odd - can dcmd_size be bigger than iov_size? Wouldn't we overwrite
> | guest memory then? And where does dcmd_size come from? I don't see it in
> | master.
>
> struct mfi_ctrl_props info;
> size_t dcmd_size = sizeof(info);
>
> -> http://git.qemu.org/?p=qemu.git;a=blob;f=hw/scsi/megasas.c;h=a63a581550a328d0326ddee4f7fe1c4ffdecc194;hb=HEAD#l1439
>
> 'dcmd_size' is same as that of 'info' object.
Ok, then this patch is definitely bogus. The guest may receive less than
the size of the info object. So we really want to have a MIN() between
the maximum allowed transfer size (sizeof(info)) and the requested size
(cmd->iov_size) here.
Alex
next prev parent reply other threads:[~2016-05-25 11:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-25 10:31 [Qemu-devel] [PATCH 0/3] Qemu: scsi: megasas: various OOB r/w access checks P J P
2016-05-25 10:31 ` [Qemu-devel] [PATCH 1/3] scsi: megasas: use appropriate property buffer size P J P
2016-05-25 11:06 ` Alexander Graf
2016-05-25 11:51 ` P J P
2016-05-25 11:53 ` Alexander Graf [this message]
2016-05-25 12:15 ` P J P
2016-05-25 12:30 ` Alexander Graf
2016-05-25 10:31 ` [Qemu-devel] [PATCH 2/3] scsi: megasas: initialise local configuration data buffer P J P
2016-05-25 11:15 ` Alexander Graf
2016-05-25 10:31 ` [Qemu-devel] [PATCH 3/3] scsi: megasas: check 'read_queue_head' index value P J P
2016-05-25 11:20 ` Alexander Graf
2016-05-25 13:21 ` Hannes Reinecke
2016-05-25 12:00 ` [Qemu-devel] [PATCH 0/3] Qemu: scsi: megasas: various OOB r/w access checks Paolo Bonzini
2016-05-25 12:08 ` Alexander Graf
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