From 0afa9626667c3659ef8bd82d42a11e39fedf235c Mon Sep 17 00:00:00 2001 From: OGAWA Hirofumi Date: Tue, 21 Aug 2018 21:59:44 -0700 Subject: 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 Reported-by: Anatoly Trosinenko Tested-by: Anatoly Trosinenko Cc: Alan Cox Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fat/fatent.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'fs/fat/fatent.c') diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c index 25d43a5e8a4d..defc2168de91 100644 --- a/fs/fat/fatent.c +++ b/fs/fat/fatent.c @@ -24,7 +24,7 @@ static void fat12_ent_blocknr(struct super_block *sb, int entry, { struct msdos_sb_info *sbi = MSDOS_SB(sb); int bytes = entry + (entry >> 1); - WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry); + WARN_ON(!fat_valid_entry(sbi, entry)); *offset = bytes & (sb->s_blocksize - 1); *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); } @@ -34,7 +34,7 @@ static void fat_ent_blocknr(struct super_block *sb, int entry, { struct msdos_sb_info *sbi = MSDOS_SB(sb); int bytes = (entry << sbi->fatent_shift); - WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry); + WARN_ON(!fat_valid_entry(sbi, entry)); *offset = bytes & (sb->s_blocksize - 1); *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); } @@ -354,7 +354,7 @@ int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) int err, offset; sector_t blocknr; - if (entry < FAT_START_ENT || sbi->max_cluster <= entry) { + if (!fat_valid_entry(sbi, entry)) { fatent_brelse(fatent); fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry); return -EIO; -- cgit v1.2.3