[PATCH v2 2/4] ses: fix possible addl_desc_ptr out-of-bounds accesses in ses_enclosure_data_process

[Tomas Henzl <thenzl@redhat.com>]

Sanitize possible addl_desc_ptr out-of-bounds accesses
in ses_enclosure_data_process.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
---
 drivers/scsi/ses.c | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
index 1ee927ac8603..896fd4f6e93d 100644
--- a/drivers/scsi/ses.c
+++ b/drivers/scsi/ses.c
@@ -433,8 +433,8 @@ int ses_match_host(struct enclosure_device *edev, void *data)
 }
 #endif  /*  0  */
 
-static void ses_process_descriptor(struct enclosure_component *ecomp,
-				   unsigned char *desc)
+static int ses_process_descriptor(struct enclosure_component *ecomp,
+				   unsigned char *desc, int max_desc_len)
 {
 	int eip = desc[0] & 0x10;
 	int invalid = desc[0] & 0x80;
@@ -445,22 +445,32 @@ static void ses_process_descriptor(struct enclosure_component *ecomp,
 	unsigned char *d;
 
 	if (invalid)
-		return;
+		return 0;
 
 	switch (proto) {
 	case SCSI_PROTOCOL_FCP:
 		if (eip) {
+			if (max_desc_len <= 7)
+				return 1;
 			d = desc + 4;
 			slot = d[3];
 		}
 		break;
 	case SCSI_PROTOCOL_SAS:
+
 		if (eip) {
+			if (max_desc_len <= 27)
+				return 1;
 			d = desc + 4;
 			slot = d[3];
 			d = desc + 8;
-		} else
+		} else {
+			if (max_desc_len <= 23)
+				return 1;
 			d = desc + 4;
+		}
+
+
 		/* only take the phy0 addr */
 		addr = (u64)d[12] << 56 |
 			(u64)d[13] << 48 |
@@ -477,6 +487,8 @@ static void ses_process_descriptor(struct enclosure_component *ecomp,
 	}
 	ecomp->slot = slot;
 	scomp->addr = addr;
+
+	return 0;
 }
 
 struct efd {
@@ -549,7 +561,7 @@ static void ses_enclosure_data_process(struct enclosure_device *edev,
 		/* skip past overall descriptor */
 		desc_ptr += len + 4;
 	}
-	if (ses_dev->page10)
+	if (ses_dev->page10 && ses_dev->page10_len > 9)
 		addl_desc_ptr = ses_dev->page10 + 8;
 	type_ptr = ses_dev->page1_types;
 	components = 0;
@@ -557,6 +569,7 @@ static void ses_enclosure_data_process(struct enclosure_device *edev,
 		for (j = 0; j < type_ptr[1]; j++) {
 			char *name = NULL;
 			struct enclosure_component *ecomp;
+			int max_desc_len;
 
 			if (desc_ptr) {
 				if (desc_ptr >= buf + page7_len) {
@@ -583,10 +596,14 @@ static void ses_enclosure_data_process(struct enclosure_device *edev,
 					ecomp = &edev->component[components++];
 
 				if (!IS_ERR(ecomp)) {
-					if (addl_desc_ptr)
-						ses_process_descriptor(
-							ecomp,
-							addl_desc_ptr);
+					if (addl_desc_ptr) {
+						max_desc_len = ses_dev->page10_len -
+						    (addl_desc_ptr - ses_dev->page10);
+						if (ses_process_descriptor(ecomp,
+						    addl_desc_ptr,
+						    max_desc_len))
+							addl_desc_ptr = NULL;
+					}
 					if (create)
 						enclosure_component_register(
 							ecomp);
-- 
2.38.1