From: Bob Copeland Date: Fri, 15 Aug 2008 07:40:47 +0000 (-0700) Subject: omfs: fix oops when file metadata is corrupted X-Git-Tag: v2.6.27-rc4~70 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9419fc1c957d600093baaea247fef23cca3b4e93;p=linux-2.6 omfs: fix oops when file metadata is corrupted A fuzzed fileystem image failed with OMFS when the extent count was used in a loop without being checked against the max number of extents. It also provoked a signed division for an array index that was checked as if unsigned, leading to index by -1. omfsck will be updated to fix these cases, in the meantime bail out gracefully. Reported-by: Eric Sesterhenn Signed-off-by: Bob Copeland Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/omfs/bitmap.c b/fs/omfs/bitmap.c index 697663b01b..e1c0ec0ae9 100644 --- a/fs/omfs/bitmap.c +++ b/fs/omfs/bitmap.c @@ -92,7 +92,7 @@ int omfs_allocate_block(struct super_block *sb, u64 block) struct buffer_head *bh; struct omfs_sb_info *sbi = OMFS_SB(sb); int bits_per_entry = 8 * sb->s_blocksize; - int map, bit; + unsigned int map, bit; int ret = 0; u64 tmp; @@ -176,7 +176,8 @@ int omfs_clear_range(struct super_block *sb, u64 block, int count) struct omfs_sb_info *sbi = OMFS_SB(sb); int bits_per_entry = 8 * sb->s_blocksize; u64 tmp; - int map, bit, ret; + unsigned int map, bit; + int ret; tmp = block; bit = do_div(tmp, bits_per_entry); diff --git a/fs/omfs/file.c b/fs/omfs/file.c index 7e2499053e..834b2331f6 100644 --- a/fs/omfs/file.c +++ b/fs/omfs/file.c @@ -26,6 +26,13 @@ static int omfs_sync_file(struct file *file, struct dentry *dentry, return err ? -EIO : 0; } +static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset) +{ + return (sbi->s_sys_blocksize - offset - + sizeof(struct omfs_extent)) / + sizeof(struct omfs_extent_entry) + 1; +} + void omfs_make_empty_table(struct buffer_head *bh, int offset) { struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset]; @@ -45,6 +52,7 @@ int omfs_shrink_inode(struct inode *inode) struct buffer_head *bh; u64 next, last; u32 extent_count; + u32 max_extents; int ret; /* traverse extent table, freeing each entry that is greater @@ -62,15 +70,18 @@ int omfs_shrink_inode(struct inode *inode) goto out; oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]); + max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START); for (;;) { - if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next)) { - brelse(bh); - goto out; - } + if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next)) + goto out_brelse; extent_count = be32_to_cpu(oe->e_extent_count); + + if (extent_count > max_extents) + goto out_brelse; + last = next; next = be64_to_cpu(oe->e_next); entry = &oe->e_entry; @@ -98,10 +109,14 @@ int omfs_shrink_inode(struct inode *inode) if (!bh) goto out; oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]); + max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT); } ret = 0; out: return ret; +out_brelse: + brelse(bh); + return ret; } static void omfs_truncate(struct inode *inode) @@ -154,9 +169,7 @@ static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe, goto out; } } - max_count = (sbi->s_sys_blocksize - OMFS_EXTENT_START - - sizeof(struct omfs_extent)) / - sizeof(struct omfs_extent_entry) + 1; + max_count = omfs_max_extents(sbi, OMFS_EXTENT_START); /* TODO: add a continuation block here */ if (be32_to_cpu(oe->e_extent_count) > max_count-1) @@ -225,6 +238,7 @@ static int omfs_get_block(struct inode *inode, sector_t block, sector_t next, offset; int ret; u64 new_block; + u32 max_extents; int extent_count; struct omfs_extent *oe; struct omfs_extent_entry *entry; @@ -238,6 +252,7 @@ static int omfs_get_block(struct inode *inode, sector_t block, goto out; oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]); + max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START); next = inode->i_ino; for (;;) { @@ -249,6 +264,9 @@ static int omfs_get_block(struct inode *inode, sector_t block, next = be64_to_cpu(oe->e_next); entry = &oe->e_entry; + if (extent_count > max_extents) + goto out_brelse; + offset = find_block(inode, entry, block, extent_count, &remain); if (offset > 0) { ret = 0; @@ -266,6 +284,7 @@ static int omfs_get_block(struct inode *inode, sector_t block, if (!bh) goto out; oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]); + max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT); } if (create) { ret = omfs_grow_extent(inode, oe, &new_block);