Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]


Groups > linux.kernel > #1696843

Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction before starting the request) breaks mtx tape library control

From Johannes Thumshirn <jthumshirn@suse.de>
Newsgroups linux.kernel
Subject Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction before starting the request) breaks mtx tape library control
Date 2017-07-26 09:40 +0200
Message-ID <u7p5f-5Ol-5@gated-at.bofh.it> (permalink)
References (5 earlier) <u4SGt-5YR-3@gated-at.bofh.it> <u5JhM-7eu-11@gated-at.bofh.it> <u5LMB-ou-7@gated-at.bofh.it> <u72il-8fe-1@gated-at.bofh.it> <u7cKK-6j1-27@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw


On Tue, Jul 25, 2017 at 01:25:07PM -0500, Jason L Tibbitts III wrote:
> >>>>> "JT" == Johannes Thumshirn <jthumshirn@suse.de> writes:
> ioctl(3, SG_IO, {interface_id='S', dxfer_direction=SG_DXFER_TO_DEV, cmd_len=12, cmdp="\xa5\x00\x00\x00\x00\x01\x03\xe9\x00\x00\x00\x00", mx_sb_len=20, iovec_count=0, dxfer_len=0, timeout=300000, flags=0, dxferp=NULL, status=0, masked_status=0, msg_status=0, sb_len_wr=0, sbp="", host_status=0, driver_status=0, resid=0, duration=0, info=0}) = -1 EINVAL (Invalid argument)

[...]
 	case SG_DXFER_TO_DEV:
  	case SG_DXFER_TO_FROM_DEV:
 		if (!hp->dxferp)
  			return false;
  		return true;

So here we go, dxfer_direction is SG_DXFER_TO_DEV, dxfer_len is 0 and dxferp
is NULL. We bail out because dxferp is NULL here.

I only looked at sg_write() and not sg_new_write() which is called by the
SG_IO path not the fops->write() path.

It's probably best to just check for dxfer_len <= 2^28 to be valid as Doug
suggested:

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 4fe606b000b4..d7ff71e0c85c 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -751,35 +751,6 @@ sg_new_write(Sg_fd *sfp, struct file *file, const char __user *buf,
 	return count;
 }
 
-static bool sg_is_valid_dxfer(sg_io_hdr_t *hp)
-{
-	switch (hp->dxfer_direction) {
-	case SG_DXFER_NONE:
-		if (hp->dxferp || hp->dxfer_len > 0)
-			return false;
-		return true;
-	case SG_DXFER_FROM_DEV:
-		/*
-		 * for SG_DXFER_FROM_DEV we always set dxfer_len to > 0. dxferp
-		 * can either be NULL or != NULL so there's no point in checking
-		 * it either. So just return true.
-		 */
-		return true;
-	case SG_DXFER_TO_DEV:
-	case SG_DXFER_TO_FROM_DEV:
-		if (!hp->dxferp || hp->dxfer_len == 0)
-			return false;
-		return true;
-	case SG_DXFER_UNKNOWN:
-		if ((!hp->dxferp && hp->dxfer_len) ||
-		    (hp->dxferp && hp->dxfer_len == 0))
-			return false;
-		return true;
-	default:
-		return false;
-	}
-}
-
 static int
 sg_common_write(Sg_fd * sfp, Sg_request * srp,
 		unsigned char *cmnd, int timeout, int blocking)
@@ -800,7 +771,7 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
 			"sg_common_write:  scsi opcode=0x%02x, cmd_size=%d\n",
 			(int) cmnd[0], (int) hp->cmd_len));
 
-	if (!sg_is_valid_dxfer(hp))
+	if (hp->dxfer_len >= SZ_256M)
 		return -EINVAL;
 
 	k = sg_start_req(srp, cmnd);

-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

Back to linux.kernel | Previous | NextPrevious in thread | Next in thread | Find similar | Unroll thread


Thread

Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction before starting the request) breaks mtx tape library control Jason L Tibbitts III <tibbs@math.uh.edu> - 2017-07-18 19:40 +0200
  Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction  before starting the request) breaks mtx tape library control Johannes Thumshirn <jthumshirn@suse.de> - 2017-07-19 09:10 +0200
    Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction before starting the request) breaks mtx tape library control Jason L Tibbitts III <tibbs@math.uh.edu> - 2017-07-19 10:20 +0200
      Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction  before starting the request) breaks mtx tape library control Johannes Thumshirn <jthumshirn@suse.de> - 2017-07-19 10:40 +0200
        Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction  before starting the request) breaks mtx tape library control Johannes Thumshirn <jthumshirn@suse.de> - 2017-07-21 18:50 +0200
          Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction before starting the request) breaks mtx tape library control Jason L Tibbitts III <tibbs@math.uh.edu> - 2017-07-21 21:30 +0200
            Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction  before starting the request) breaks mtx tape library control Johannes Thumshirn <jthumshirn@suse.de> - 2017-07-25 09:20 +0200
              Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction before starting the request) breaks mtx tape library control Jason L Tibbitts III <tibbs@math.uh.edu> - 2017-07-25 20:30 +0200
                Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction  before starting the request) breaks mtx tape library control Johannes Thumshirn <jthumshirn@suse.de> - 2017-07-26 09:40 +0200
                Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction before starting the request) breaks mtx tape library control Jason L Tibbitts III <tibbs@math.uh.edu> - 2017-07-26 22:20 +0200
        Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction  before starting the request) breaks mtx tape library control Douglas Gilbert <dgilbert@interlog.com> - 2017-07-25 21:10 +0200
          Re: [REGRESSION] 28676d869bbb (scsi: sg: check for valid direction  before starting the request) breaks mtx tape library control Johannes Thumshirn <jthumshirn@suse.de> - 2017-07-26 09:30 +0200

csiph-web