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| author | OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> | 2018-08-21 21:59:44 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-22 10:52:50 -0700 |
| commit | 0afa9626667c3659ef8bd82d42a11e39fedf235c (patch) | |
| tree | 9b5c96147d7eb18dc6d6b148e2f02c76b8ef9053 /fs/fat/cache.c | |
| parent | f663b5b38fffeb31841f8bfaf0ef87a445b0ffee (diff) | |
| download | linux-0afa9626667c3659ef8bd82d42a11e39fedf235c.tar.gz linux-0afa9626667c3659ef8bd82d42a11e39fedf235c.tar.bz2 linux-0afa9626667c3659ef8bd82d42a11e39fedf235c.zip | |
fat: validate ->i_start before using
On corrupted FATfs may have invalid ->i_start. To handle it, this checks
->i_start before using, and return proper error code.
Link: http://lkml.kernel.org/r/87o9f8y1t5.fsf_-_@mail.parknet.co.jp
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Tested-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/fat/cache.c')
| -rw-r--r-- | fs/fat/cache.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/fs/fat/cache.c b/fs/fat/cache.c index e9bed49df6b7..78d501c1fb65 100644 --- a/fs/fat/cache.c +++ b/fs/fat/cache.c @@ -225,7 +225,8 @@ static inline void cache_init(struct fat_cache_id *cid, int fclus, int dclus) int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus) { struct super_block *sb = inode->i_sb; - const int limit = sb->s_maxbytes >> MSDOS_SB(sb)->cluster_bits; + struct msdos_sb_info *sbi = MSDOS_SB(sb); + const int limit = sb->s_maxbytes >> sbi->cluster_bits; struct fat_entry fatent; struct fat_cache_id cid; int nr; @@ -234,6 +235,12 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus) *fclus = 0; *dclus = MSDOS_I(inode)->i_start; + if (!fat_valid_entry(sbi, *dclus)) { + fat_fs_error_ratelimit(sb, + "%s: invalid start cluster (i_pos %lld, start %08x)", + __func__, MSDOS_I(inode)->i_pos, *dclus); + return -EIO; + } if (cluster == 0) return 0; @@ -250,9 +257,8 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus) /* prevent the infinite loop of cluster chain */ if (*fclus > limit) { fat_fs_error_ratelimit(sb, - "%s: detected the cluster chain loop" - " (i_pos %lld)", __func__, - MSDOS_I(inode)->i_pos); + "%s: detected the cluster chain loop (i_pos %lld)", + __func__, MSDOS_I(inode)->i_pos); nr = -EIO; goto out; } @@ -262,9 +268,8 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus) goto out; else if (nr == FAT_ENT_FREE) { fat_fs_error_ratelimit(sb, - "%s: invalid cluster chain (i_pos %lld)", - __func__, - MSDOS_I(inode)->i_pos); + "%s: invalid cluster chain (i_pos %lld)", + __func__, MSDOS_I(inode)->i_pos); nr = -EIO; goto out; } else if (nr == FAT_ENT_EOF) { |