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omfs: fix oops when file metadata is corrupted

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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 <snakebyte@gmx.de>
Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Bob Copeland 2008-08-15 00:40:47 -07:00 committed by Linus Torvalds
parent c963343a11
commit 9419fc1c95
2 changed files with 29 additions and 9 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
fs/omfs/bitmap.c
View file

@ -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);

33
fs/omfs/file.c
View file

@ -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);