1 files changed, 36 insertions, 9 deletions

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 9121938..3306b9f 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -76,6 +76,9 @@
 
 #define UDF_DEFAULT_BLOCKSIZE 2048
 
+#define VSD_FIRST_SECTOR_OFFSET		32768
+#define VSD_MAX_SECTOR_OFFSET		0x800000
+
 enum { UDF_MAX_LINKS = 0xffff };
 
 /* These are the "meat" - everything else is stuffing */
@@ -685,7 +688,7 @@ out_unlock:
 static loff_t udf_check_vsd(struct super_block *sb)
 {
 	struct volStructDesc *vsd = NULL;
-	loff_t sector = 32768;
+	loff_t sector = VSD_FIRST_SECTOR_OFFSET;
 	int sectorsize;
 	struct buffer_head *bh = NULL;
 	int nsr02 = 0;
@@ -703,8 +706,18 @@ static loff_t udf_check_vsd(struct super_block *sb)
 	udf_debug("Starting at sector %u (%ld byte sectors)\n",
 		  (unsigned int)(sector >> sb->s_blocksize_bits),
 		  sb->s_blocksize);
-	/* Process the sequence (if applicable) */
-	for (; !nsr02 && !nsr03; sector += sectorsize) {
+	/* Process the sequence (if applicable). The hard limit on the sector
+	 * offset is arbitrary, hopefully large enough so that all valid UDF
+	 * filesystems will be recognised. There is no mention of an upper
+	 * bound to the size of the volume recognition area in the standard.
+	 *  The limit will prevent the code to read all the sectors of a
+	 * specially crafted image (like a bluray disc full of CD001 sectors),
+	 * potentially causing minutes or even hours of uninterruptible I/O
+	 * activity. This actually happened with uninitialised SSD partitions
+	 * (all 0xFF) before the check for the limit and all valid IDs were
+	 * added */
+	for (; !nsr02 && !nsr03 && sector < VSD_MAX_SECTOR_OFFSET;
+	     sector += sectorsize) {
 		/* Read a block */
 		bh = udf_tread(sb, sector >> sb->s_blocksize_bits);
 		if (!bh)
@@ -714,10 +727,7 @@ static loff_t udf_check_vsd(struct super_block *sb)
 		vsd = (struct volStructDesc *)(bh->b_data +
 					      (sector & (sb->s_blocksize - 1)));
 
-		if (vsd->stdIdent[0] == 0) {
-			brelse(bh);
-			break;
-		} else if (!strncmp(vsd->stdIdent, VSD_STD_ID_CD001,
+		if (!strncmp(vsd->stdIdent, VSD_STD_ID_CD001,
 				    VSD_STD_ID_LEN)) {
 			switch (vsd->structType) {
 			case 0:
@@ -753,6 +763,17 @@ static loff_t udf_check_vsd(struct super_block *sb)
 		else if (!strncmp(vsd->stdIdent, VSD_STD_ID_NSR03,
 				    VSD_STD_ID_LEN))
 			nsr03 = sector;
+		else if (!strncmp(vsd->stdIdent, VSD_STD_ID_BOOT2,
+				    VSD_STD_ID_LEN))
+			; /* nothing */
+		else if (!strncmp(vsd->stdIdent, VSD_STD_ID_CDW02,
+				    VSD_STD_ID_LEN))
+			; /* nothing */
+		else {
+			/* invalid id : end of volume recognition area */
+			brelse(bh);
+			break;
+		}
 		brelse(bh);
 	}
 
@@ -760,7 +781,8 @@ static loff_t udf_check_vsd(struct super_block *sb)
 		return nsr03;
 	else if (nsr02)
 		return nsr02;
-	else if (sector - (sbi->s_session << sb->s_blocksize_bits) == 32768)
+	else if (!bh && sector - (sbi->s_session << sb->s_blocksize_bits) ==
+			VSD_FIRST_SECTOR_OFFSET)
 		return -1;
 	else
 		return 0;
@@ -1270,6 +1292,9 @@ static int udf_load_partdesc(struct super_block *sb, sector_t block)
 	 * PHYSICAL partitions are already set up
 	 */
 	type1_idx = i;
+#ifdef UDFFS_DEBUG
+	map = NULL; /* supress 'maybe used uninitialized' warning */
+#endif
 	for (i = 0; i < sbi->s_partitions; i++) {
 		map = &sbi->s_partmaps[i];
 
@@ -1891,7 +1916,9 @@ static int udf_load_vrs(struct super_block *sb, struct udf_options *uopt,
 			return 0;
 		}
 		if (nsr_off == -1)
-			udf_debug("Failed to read byte 32768. Assuming open disc. Skipping validity check\n");
+			udf_debug("Failed to read sector at offset %d. "
+				  "Assuming open disc. Skipping validity "
+				  "check\n", VSD_FIRST_SECTOR_OFFSET);
 		if (!sbi->s_last_block)
 			sbi->s_last_block = udf_get_last_block(sb);
 	} else {