linux-kernel - Re: scsi: sg: assorted memory corruptions

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Date:   Mon, 22 Jan 2018 16:30:35 +0000
From:   Bart Van Assche <Bart.VanAssche@....com>
To:     "jejb@...ux.vnet.ibm.com" <jejb@...ux.vnet.ibm.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "dgilbert@...erlog.com" <dgilbert@...erlog.com>,
        "dvyukov@...gle.com" <dvyukov@...gle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "ben.hutchings@...ethink.co.uk" <ben.hutchings@...ethink.co.uk>
CC:     "syzkaller@...glegroups.com" <syzkaller@...glegroups.com>
Subject: Re: scsi: sg: assorted memory corruptions

On Mon, 2018-01-22 at 12:06 +0100, Dmitry Vyukov wrote:
> general protection fault: 0000 [#1] SMP KASAN

How about the untested patch below?

Thanks,

Bart.


diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index cd9b6ebd7257..04a644b39d79 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -627,6 +627,10 @@ sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
 	mutex_unlock(&sfp->f_mutex);
 	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sdp,
 		"sg_write:   scsi opcode=0x%02x, cmd_size=%d\n", (int) opcode, cmd_size));
+	if (cmd_size > sizeof(cmnd)) {
+		sg_remove_request(sfp, srp);
+		return -EFAULT;
+	}
 	/* Determine buffer size.  */
 	input_size = count - cmd_size;
 	mxsize = max(input_size, old_hdr.reply_len);