From 5e7ff2ca7f2da55fe777167849d0c93403bd0dc8 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 23 Jun 2016 15:05:26 -0400 Subject: [PATCH] SCSI: fix new bug in scsi_dev_info_list string matching 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 Fixes: b704f70ce200 ("SCSI: fix bug in scsi_dev_info_list matching") Tested-by: Wilfried Klaebe CC: # v4.4+ Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_devinfo.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/scsi/scsi_devinfo.c b/drivers/scsi/scsi_devinfo.c index ff41c310c900..eaccd651ccda 100644 --- a/drivers/scsi/scsi_devinfo.c +++ b/drivers/scsi/scsi_devinfo.c @@ -429,7 +429,7 @@ static struct scsi_dev_info_list *scsi_dev_info_list_find(const char *vendor, * 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_dev_info_list_find(const char *vendor, 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_dev_info_list_find(const char *vendor, * 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 {