4.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
commit 5e7ff2ca7f2da55fe777167849d0c93403bd0dc8 upstream.
Commit b704f70ce200 ("SCSI: fix bug in scsi_dev_info_list matching")
changed the way vendor- and model-string matching was carried out in the
routine that looks up entries in a SCSI devinfo list. The new matching
code failed to take into account the case of a maximum-length string; in
such cases it could end up testing for a terminating '\0' byte beyond
the end of the memory allocated to the string. This out-of-bounds bug
was detected by UBSAN.
I don't know if anybody has actually encountered this bug. The symptom
would be that a device entry in the blacklist might not be matched
properly if it contained an 8-character vendor name or a 16-character
model name. Such entries certainly exist in scsi_static_device_list.
This patch fixes the problem by adding a check for a maximum-length
string before the '\0' test.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Fixes: b704f70ce200 ("SCSI: fix bug in scsi_dev_info_list matching")
Tested-by: Wilfried Klaebe <linux-kernel@xxxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/scsi/scsi_devinfo.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/drivers/scsi/scsi_devinfo.c
+++ b/drivers/scsi/scsi_devinfo.c
@@ -429,7 +429,7 @@ static struct scsi_dev_info_list *scsi_d
* here, and we don't know what device it is
* trying to work with, leave it as-is.
*/
- vmax = 8; /* max length of vendor */
+ vmax = sizeof(devinfo->vendor);
vskip = vendor;
while (vmax > 0 && *vskip == ' ') {
vmax--;
@@ -439,7 +439,7 @@ static struct scsi_dev_info_list *scsi_d
while (vmax > 0 && vskip[vmax - 1] == ' ')
--vmax;
- mmax = 16; /* max length of model */
+ mmax = sizeof(devinfo->model);
mskip = model;
while (mmax > 0 && *mskip == ' ') {
mmax--;
@@ -455,10 +455,12 @@ static struct scsi_dev_info_list *scsi_d
* Behave like the older version of get_device_flags.
*/
if (memcmp(devinfo->vendor, vskip, vmax) ||
- devinfo->vendor[vmax])
+ (vmax < sizeof(devinfo->vendor) &&
+ devinfo->vendor[vmax]))
continue;
if (memcmp(devinfo->model, mskip, mmax) ||
- devinfo->model[mmax])
+ (mmax < sizeof(devinfo->model) &&
+ devinfo->model[mmax]))
continue;
return devinfo;
} else {
--
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