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-rw-r--r--fs/udf/super.c45
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 {
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