linux-kernel - [PATCH] scsi_lib: Fix priority order when generating LUN ID

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Date:   Tue, 24 Jan 2017 09:58:30 +0000
From:   Sylvain Munaut <s.munaut@...tever-company.com>
To:     linux-kernel@...r.kernel.org
Cc:     Hannes Reinecke <hare@...e.com>,
        Bart Van Assche <bart.vanassche@...disk.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Sylvain Munaut <s.munaut@...tever-company.com>
Subject: [PATCH] scsi_lib: Fix priority order when generating LUN ID

Previously the order described in the comment wasn't the actual
order that was considered. And the result also depended on the orders
of the various ID in the pg83 data.

Signed-off-by: Sylvain Munaut <s.munaut@...tever-company.com>
---
 drivers/scsi/scsi_lib.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index e9e1e14..d737183 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -3099,7 +3099,7 @@ EXPORT_SYMBOL(sdev_enable_disk_events);
  */
 int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
 {
-	u8 cur_id_type = 0xff;
+	int cur_id_pref = 0;
 	u8 cur_id_size = 0;
 	unsigned char *d, *cur_id_str;
 	unsigned char __rcu *vpd_pg83;
@@ -3142,30 +3142,23 @@ int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
 		switch (d[1] & 0xf) {
 		case 0x1:
 			/* T10 Vendor ID */
-			if (cur_id_size > d[3])
-				break;
-			/* Prefer anything */
-			if (cur_id_type > 0x01 && cur_id_type != 0xff)
+			if (cur_id_pref > 1 || (cur_id_pref == 1 && cur_id_size > d[3]))
 				break;
 			cur_id_size = d[3];
 			if (cur_id_size + 4 > id_len)
 				cur_id_size = id_len - 4;
 			cur_id_str = d + 4;
-			cur_id_type = d[1] & 0xf;
+			cur_id_pref = 1;
 			id_size = snprintf(id, id_len, "t10.%*pE",
 					   cur_id_size, cur_id_str);
 			break;
 		case 0x2:
 			/* EUI-64 */
-			if (cur_id_size > d[3])
-				break;
-			/* Prefer NAA IEEE Registered Extended */
-			if (cur_id_type == 0x3 &&
-			    cur_id_size == d[3])
+			if (cur_id_pref > 2 || (cur_id_pref == 2 && cur_id_size >= d[3]))
 				break;
 			cur_id_size = d[3];
 			cur_id_str = d + 4;
-			cur_id_type = d[1] & 0xf;
+			cur_id_pref = 2;
 			switch (cur_id_size) {
 			case 8:
 				id_size = snprintf(id, id_len,
@@ -3189,11 +3182,11 @@ int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
 			break;
 		case 0x3:
 			/* NAA */
-			if (cur_id_size > d[3])
+			if (cur_id_pref > 2 || (cur_id_pref == 2 && cur_id_size > d[3]))
 				break;
 			cur_id_size = d[3];
 			cur_id_str = d + 4;
-			cur_id_type = d[1] & 0xf;
+			cur_id_pref = 2;
 			switch (cur_id_size) {
 			case 8:
 				id_size = snprintf(id, id_len,
@@ -3212,6 +3205,8 @@ int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
 			break;
 		case 0x8:
 			/* SCSI name string */
+			if (cur_id_pref > 3 || (cur_id_pref == 3 && cur_id_size > d[3]))
+				break;
 			if (cur_id_size + 4 > d[3])
 				break;
 			/* Prefer others for truncated descriptor */
@@ -3219,7 +3214,7 @@ int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
 				break;
 			cur_id_size = id_size = d[3];
 			cur_id_str = d + 4;
-			cur_id_type = d[1] & 0xf;
+			cur_id_pref = 3;
 			if (cur_id_size >= id_len)
 				cur_id_size = id_len - 1;
 			memcpy(id, cur_id_str, cur_id_size);
-- 
2.1.4