[SCSI] eliminate potential kmalloc failure in scsi_get_vpd_page()

The best way to fix this is to eliminate the intenal kmalloc() and
make the caller allocate the required amount of storage.
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/scsi.c

@@ -1026,55 +1026,39 @@ static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
  * responsible for calling kfree() on this pointer when it is no longer
  * needed.  If we cannot retrieve the VPD page this routine returns %NULL.
  */
-unsigned char *scsi_get_vpd_page(struct scsi_device *sdev, u8 page)
+int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
+		      int buf_len)
 {
 	int i, result;
-	unsigned int len;
-	const unsigned int init_vpd_len = 255;
-	unsigned char *buf = kmalloc(init_vpd_len, GFP_KERNEL);
-
-	if (!buf)
-		return NULL;
 
 	/* Ask for all the pages supported by this device */
-	result = scsi_vpd_inquiry(sdev, buf, 0, init_vpd_len);
+	result = scsi_vpd_inquiry(sdev, buf, 0, buf_len);
 	if (result)
 		goto fail;
 
 	/* If the user actually wanted this page, we can skip the rest */
 	if (page == 0)
-		return buf;
+		return -EINVAL;
 
-	for (i = 0; i < buf[3]; i++)
+	for (i = 0; i < min((int)buf[3], buf_len - 4); i++)
 		if (buf[i + 4] == page)
 			goto found;
+
+	if (i < buf[3] && i > buf_len)
+		/* ran off the end of the buffer, give us benefit of doubt */
+		goto found;
 	/* The device claims it doesn't support the requested page */
 	goto fail;
 
  found:
-	result = scsi_vpd_inquiry(sdev, buf, page, 255);
-	if (result)
-		goto fail;
-
-	/*
-	 * Some pages are longer than 255 bytes.  The actual length of
-	 * the page is returned in the header.
-	 */
-	len = ((buf[2] << 8) | buf[3]) + 4;
-	if (len <= init_vpd_len)
-		return buf;
-
-	kfree(buf);
-	buf = kmalloc(len, GFP_KERNEL);
-	result = scsi_vpd_inquiry(sdev, buf, page, len);
+	result = scsi_vpd_inquiry(sdev, buf, page, buf_len);
 	if (result)
 		goto fail;
 
-	return buf;
+	return 0;
 
  fail:
-	kfree(buf);
-	return NULL;
+	return -EINVAL;
 }
 EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
 

drivers/scsi/sd.c

@@ -1946,13 +1946,13 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
 {
 	struct request_queue *q = sdkp->disk->queue;
 	unsigned int sector_sz = sdkp->device->sector_size;
-	char *buffer;
+	const int vpd_len = 32;
+	unsigned char *buffer = kmalloc(vpd_len, GFP_KERNEL);
 
+	if (!buffer ||
 	    /* Block Limits VPD */
-	buffer = scsi_get_vpd_page(sdkp->device, 0xb0);
-
-	if (buffer == NULL)
-		return;
+	    scsi_get_vpd_page(sdkp->device, 0xb0, buffer, vpd_len))
+		goto out;
 
 	blk_queue_io_min(sdkp->disk->queue,
 			 get_unaligned_be16(&buffer[6]) * sector_sz);
@@ -1984,6 +1984,7 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
 				get_unaligned_be32(&buffer[32]) & ~(1 << 31);
 	}
 
+ out:
 	kfree(buffer);
 }
 
@@ -1993,20 +1994,23 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
  */
 static void sd_read_block_characteristics(struct scsi_disk *sdkp)
 {
-	char *buffer;
+	unsigned char *buffer;
 	u16 rot;
+	const int vpd_len = 32;
 
-	/* Block Device Characteristics VPD */
-	buffer = scsi_get_vpd_page(sdkp->device, 0xb1);
+	buffer = kmalloc(vpd_len, GFP_KERNEL);
 
-	if (buffer == NULL)
-		return;
+	if (!buffer ||
+	    /* Block Device Characteristics VPD */
+	    scsi_get_vpd_page(sdkp->device, 0xb1, buffer, vpd_len))
+		goto out;
 
 	rot = get_unaligned_be16(&buffer[4]);
 
 	if (rot == 1)
 		queue_flag_set_unlocked(QUEUE_FLAG_NONROT, sdkp->disk->queue);
 
+ out:
 	kfree(buffer);
 }
 

drivers/scsi/ses.c

@@ -448,13 +448,17 @@ static void ses_match_to_enclosure(struct enclosure_device *edev,
 		.addr = 0,
 	};
 
-	buf = scsi_get_vpd_page(sdev, 0x83);
-	if (!buf)
-		return;
+	buf = kmalloc(INIT_ALLOC_SIZE, GFP_KERNEL);
+	if (!buf || scsi_get_vpd_page(sdev, 0x83, buf, INIT_ALLOC_SIZE))
+		goto free;
 
 	ses_enclosure_data_process(edev, to_scsi_device(edev->edev.parent), 0);
 
 	vpd_len = ((buf[2] << 8) | buf[3]) + 4;
+	kfree(buf);
+	buf = kmalloc(vpd_len, GFP_KERNEL);
+	if (!buf ||scsi_get_vpd_page(sdev, 0x83, buf, vpd_len))
+		goto free;
 
 	desc = buf + 4;
 	while (desc < buf + vpd_len) {

include/scsi/scsi_device.h

@@ -348,7 +348,8 @@ extern int scsi_mode_select(struct scsi_device *sdev, int pf, int sp,
 			    struct scsi_sense_hdr *);
 extern int scsi_test_unit_ready(struct scsi_device *sdev, int timeout,
 				int retries, struct scsi_sense_hdr *sshdr);
-extern unsigned char *scsi_get_vpd_page(struct scsi_device *, u8 page);
+extern int scsi_get_vpd_page(struct scsi_device *, u8 page, unsigned char *buf,
+			     int buf_len);
 extern int scsi_device_set_state(struct scsi_device *sdev,
 				 enum scsi_device_state state);
 extern struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,