udf: Fortify LVID loading

A user has reported an oops in udf_statfs() that was caused by
numOfPartitions entry in LVID structure being corrupted. Fix the problem
by verifying whether numOfPartitions makes sense at least to the extent
that LVID fits into a single block as it should.

Reported-by: Juergen Weigert <jw@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>

3 files changed, 48 insertions, 34 deletions

diff --git a/fs/udf/ialloc.c b/fs/udf/ialloc.c
index 7e5aae4bf46f..6eaf5edf1ea1 100644
--- a/fs/udf/ialloc.c
+++ b/fs/udf/ialloc.c
@@ -30,18 +30,17 @@ void udf_free_inode(struct inode *inode)
 {
         struct super_block *sb = inode->i_sb;
         struct udf_sb_info *sbi = UDF_SB(sb);
+        struct logicalVolIntegrityDescImpUse *lvidiu = udf_sb_lvidiu(sb);
 
-        mutex_lock(&sbi->s_alloc_mutex);
-        if (sbi->s_lvid_bh) {
-                struct logicalVolIntegrityDescImpUse *lvidiu =
-                                                        udf_sb_lvidiu(sbi);
+        if (lvidiu) {
+                mutex_lock(&sbi->s_alloc_mutex);
                 if (S_ISDIR(inode->i_mode))
                         le32_add_cpu(&lvidiu->numDirs, -1);
                 else
                         le32_add_cpu(&lvidiu->numFiles, -1);
                 udf_updated_lvid(sb);
+                mutex_unlock(&sbi->s_alloc_mutex);
         }
-        mutex_unlock(&sbi->s_alloc_mutex);
 
         udf_free_blocks(sb, NULL, &UDF_I(inode)->i_location, 0, 1);
 }
@@ -55,6 +54,7 @@ struct inode *udf_new_inode(struct inode *dir, umode_t mode, int *err)
         uint32_t start = UDF_I(dir)->i_location.logicalBlockNum;
         struct udf_inode_info *iinfo;
         struct udf_inode_info *dinfo = UDF_I(dir);
+        struct logicalVolIntegrityDescImpUse *lvidiu;
 
         inode = new_inode(sb);
 
@@ -92,12 +92,10 @@ struct inode *udf_new_inode(struct inode *dir, umode_t mode, int *err)
                 return NULL;
         }
 
-        if (sbi->s_lvid_bh) {
-                struct logicalVolIntegrityDescImpUse *lvidiu;
-
+        lvidiu = udf_sb_lvidiu(sb);
+        if (lvidiu) {
                 iinfo->i_unique = lvid_get_unique_id(sb);
                 mutex_lock(&sbi->s_alloc_mutex);
-                lvidiu = udf_sb_lvidiu(sbi);
                 if (S_ISDIR(mode))
                         le32_add_cpu(&lvidiu->numDirs, 1);
                 else
diff --git a/fs/udf/super.c b/fs/udf/super.c
index 839a2bad7f45..91219385691d 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -94,13 +94,25 @@ static unsigned int udf_count_free(struct super_block *);
 static int udf_statfs(struct dentry *, struct kstatfs *);
 static int udf_show_options(struct seq_file *, struct dentry *);
 
-struct logicalVolIntegrityDescImpUse *udf_sb_lvidiu(struct udf_sb_info *sbi)
+struct logicalVolIntegrityDescImpUse *udf_sb_lvidiu(struct super_block *sb)
 {
-        struct logicalVolIntegrityDesc *lvid =
-                (struct logicalVolIntegrityDesc *)sbi->s_lvid_bh->b_data;
-        __u32 number_of_partitions = le32_to_cpu(lvid->numOfPartitions);
-        __u32 offset = number_of_partitions * 2 *
-                                sizeof(uint32_t)/sizeof(uint8_t);
+        struct logicalVolIntegrityDesc *lvid;
+        unsigned int partnum;
+        unsigned int offset;
+
+        if (!UDF_SB(sb)->s_lvid_bh)
+                return NULL;
+        lvid = (struct logicalVolIntegrityDesc *)UDF_SB(sb)->s_lvid_bh->b_data;
+        partnum = le32_to_cpu(lvid->numOfPartitions);
+        if ((sb->s_blocksize - sizeof(struct logicalVolIntegrityDescImpUse) -
+             offsetof(struct logicalVolIntegrityDesc, impUse)) /
+             (2 * sizeof(uint32_t)) < partnum) {
+                udf_err(sb, "Logical volume integrity descriptor corrupted "
+                        "(numOfPartitions = %u)!\n", partnum);
+                return NULL;
+        }
+        /* The offset is to skip freeSpaceTable and sizeTable arrays */
+        offset = partnum * 2 * sizeof(uint32_t);
         return (struct logicalVolIntegrityDescImpUse *)&(lvid->impUse[offset]);
 }
 
@@ -629,9 +641,10 @@ static int udf_remount_fs(struct super_block *sb, int *flags, char *options)
         struct udf_options uopt;
         struct udf_sb_info *sbi = UDF_SB(sb);
         int error = 0;
+        struct logicalVolIntegrityDescImpUse *lvidiu = udf_sb_lvidiu(sb);
 
-        if (sbi->s_lvid_bh) {
-                int write_rev = le16_to_cpu(udf_sb_lvidiu(sbi)->minUDFWriteRev);
+        if (lvidiu) {
+                int write_rev = le16_to_cpu(lvidiu->minUDFWriteRev);
                 if (write_rev > UDF_MAX_WRITE_VERSION && !(*flags & MS_RDONLY))
                         return -EACCES;
         }
@@ -1905,11 +1918,12 @@ static void udf_open_lvid(struct super_block *sb)
 
         if (!bh)
                 return;
-
-        mutex_lock(&sbi->s_alloc_mutex);
         lvid = (struct logicalVolIntegrityDesc *)bh->b_data;
-        lvidiu = udf_sb_lvidiu(sbi);
+        lvidiu = udf_sb_lvidiu(sb);
+        if (!lvidiu)
+                return;
 
+        mutex_lock(&sbi->s_alloc_mutex);
         lvidiu->impIdent.identSuffix[0] = UDF_OS_CLASS_UNIX;
         lvidiu->impIdent.identSuffix[1] = UDF_OS_ID_LINUX;
         udf_time_to_disk_stamp(&lvid->recordingDateAndTime,
@@ -1937,10 +1951,12 @@ static void udf_close_lvid(struct super_block *sb)
 
         if (!bh)
                 return;
+        lvid = (struct logicalVolIntegrityDesc *)bh->b_data;
+        lvidiu = udf_sb_lvidiu(sb);
+        if (!lvidiu)
+                return;
 
         mutex_lock(&sbi->s_alloc_mutex);
-        lvid = (struct logicalVolIntegrityDesc *)bh->b_data;
-        lvidiu = udf_sb_lvidiu(sbi);
         lvidiu->impIdent.identSuffix[0] = UDF_OS_CLASS_UNIX;
         lvidiu->impIdent.identSuffix[1] = UDF_OS_ID_LINUX;
         udf_time_to_disk_stamp(&lvid->recordingDateAndTime, CURRENT_TIME);
@@ -2093,15 +2109,19 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 
         if (sbi->s_lvid_bh) {
                 struct logicalVolIntegrityDescImpUse *lvidiu =
-                                                        udf_sb_lvidiu(sbi);
-                uint16_t minUDFReadRev = le16_to_cpu(lvidiu->minUDFReadRev);
-                uint16_t minUDFWriteRev = le16_to_cpu(lvidiu->minUDFWriteRev);
-                /* uint16_t maxUDFWriteRev =
-                                le16_to_cpu(lvidiu->maxUDFWriteRev); */
+                                                        udf_sb_lvidiu(sb);
+                uint16_t minUDFReadRev;
+                uint16_t minUDFWriteRev;
 
+                if (!lvidiu) {
+                        ret = -EINVAL;
+                        goto error_out;
+                }
+                minUDFReadRev = le16_to_cpu(lvidiu->minUDFReadRev);
+                minUDFWriteRev = le16_to_cpu(lvidiu->minUDFWriteRev);
                 if (minUDFReadRev > UDF_MAX_READ_VERSION) {
                         udf_err(sb, "minUDFReadRev=%x (max is %x)\n",
-                                le16_to_cpu(lvidiu->minUDFReadRev),
+                                minUDFReadRev,
                                 UDF_MAX_READ_VERSION);
                         ret = -EINVAL;
                         goto error_out;
@@ -2265,11 +2285,7 @@ static int udf_statfs(struct dentry *dentry, struct kstatfs *buf)
         struct logicalVolIntegrityDescImpUse *lvidiu;
         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 
-        if (sbi->s_lvid_bh != NULL)
-                lvidiu = udf_sb_lvidiu(sbi);
-        else
-                lvidiu = NULL;
-
+        lvidiu = udf_sb_lvidiu(sb);
         buf->f_type = UDF_SUPER_MAGIC;
         buf->f_bsize = sb->s_blocksize;
         buf->f_blocks = sbi->s_partmaps[sbi->s_partition].s_partition_len;
diff --git a/fs/udf/udf_sb.h b/fs/udf/udf_sb.h
index ed401e94aa8c..1f32c7bd9f57 100644
--- a/fs/udf/udf_sb.h
+++ b/fs/udf/udf_sb.h
@@ -162,7 +162,7 @@ static inline struct udf_sb_info *UDF_SB(struct super_block *sb)
         return sb->s_fs_info;
 }
 
-struct logicalVolIntegrityDescImpUse *udf_sb_lvidiu(struct udf_sb_info *sbi);
+struct logicalVolIntegrityDescImpUse *udf_sb_lvidiu(struct super_block *sb);
 
 int udf_compute_nr_groups(struct super_block *sb, u32 partition);