fat: use fat_fs_error() instead of BUG_ON() in __fat_get_block()

If file size and FAT cluster chain is not matched (corrupted image), we
can hit BUG_ON(!phys) in __fat_get_block().

So, use fat_fs_error() instead.

[hirofumi@mail.parknet.co.jp: fix printk warning]
Link: http://lkml.kernel.org/r/87po12aq5p.fsf@mail.parknet.co.jp
Link: http://lkml.kernel.org/r/874lilcu67.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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index ffbbf05..4f818f7 100644 (file)
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -158,8 +158,14 @@ static inline int __fat_get_block(struct inode *inode, sector_t iblock,
        err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
        if (err)
                return err;
+       if (!phys) {
+               fat_fs_error(sb,
+                            "invalid FAT chain (i_pos %lld, last_block %llu)",
+                            MSDOS_I(inode)->i_pos,
+                            (unsigned long long)last_block);
+               return -EIO;
+       }
 
-       BUG_ON(!phys);
        BUG_ON(*max_blocks != mapped_blocks);
        set_buffer_new(bh_result);
        map_bh(bh_result, sb, phys);