[PATCH AUTOSEL for 4.9 156/219] scsi: sg: check for valid direction before starting the request

Sasha Levin
2018-03-03T22:35:54Z

From: Johannes Thumshirn <jthumshirn@suse.de>

[ Upstream commit 28676d869bbb5257b5f14c0c95ad3af3a7019dd5 ]

Check for a valid direction before starting the request, otherwise we
risk running into an assertion in the scsi midlayer checking for valid
requests.

[mkp: fixed typo]

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Link: http://www.spinics.net/lists/linux-scsi/msg104400.html
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Hannes Reinecke <hare@suse.com>
Tested-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/scsi/sg.c | 46 ++++++++++++++++++++++++++++++++++------------
1 file changed, 34 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index cd9537ddc19f..6b6064dc3467 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -663,18 +663,14 @@ sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
* is a non-zero input_size, so emit a warning.
*/
if (hp->dxfer_direction == SG_DXFER_TO_FROM_DEV) {
- static char cmd[TASK_COMM_LEN];
- if (strcmp(current->comm, cmd)) {
- printk_ratelimited(KERN_WARNING
- "sg_write: data in/out %d/%d bytes "
- "for SCSI command 0x%x-- guessing "
- "data in;\n program %s not setting "
- "count and/or reply_len properly\n",
- old_hdr.reply_len - (int)SZ_SG_HEADER,
- input_size, (unsigned int) cmnd[0],
- current->comm);
- strcpy(cmd, current->comm);
- }
+ printk_ratelimited(KERN_WARNING
+ "sg_write: data in/out %d/%d bytes "
+ "for SCSI command 0x%x-- guessing "
+ "data in;\n program %s not setting "
+ "count and/or reply_len properly\n",
+ old_hdr.reply_len - (int)SZ_SG_HEADER,
+ input_size, (unsigned int) cmnd[0],
+ current->comm);
}
k = sg_common_write(sfp, srp, cmnd, sfp->timeout, blocking);
return (k < 0) ? k : count;
@@ -753,6 +749,29 @@ 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_TO_DEV:
+ case SG_DXFER_FROM_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)
@@ -773,6 +792,9 @@ 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))
+ return -EINVAL;
+
k = sg_start_req(srp, cmnd);
if (k) {
SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sfp->parentdp,
--
2.14.1