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linux/fs/hfs/extent.c
Colin Ian King 6c9a3f843a fs/hfs/extent.c: fix array out of bounds read of array extent 
Currently extent and index i are both being incremented causing an array
out of bounds read on extent[i].  Fix this by removing the extraneous
increment of extent.

Ernesto said:

: This is only triggered when deleting a file with a resource fork.  I
: may be wrong because the documentation isn't clear, but I don't think
: you can create those under linux.  So I guess nobody was testing them.
:
: > A disk space leak, perhaps?
:
: That's what it looks like in general.  hfs_free_extents() won't do
: anything if the block count doesn't add up, and the error will be
: ignored.  Now, if the block count randomly does add up, we could see
: some corruption.

Detected by CoverityScan, CID#711541 ("Out of bounds read")

Link: http://lkml.kernel.org/r/20180831140538.31566-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Ernesto A. Fernndez <ernesto.mnd.fernandez@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hin-Tak Leung <htl10@users.sourceforge.net>
Cc: Vyacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-31 08:54:13 -07:00

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/*
* linux/fs/hfs/extent.c
*
* Copyright (C) 1995-1997 Paul H. Hargrove
* (C) 2003 Ardis Technologies <roman@ardistech.com>
* This file may be distributed under the terms of the GNU General Public License.
*
* This file contains the functions related to the extents B-tree.
*/
#include <linux/pagemap.h>
#include "hfs_fs.h"
#include "btree.h"
/*================ File-local functions ================*/
/*
* build_key
*/
static void hfs_ext_build_key(hfs_btree_key *key, u32 cnid, u16 block, u8 type)
{
key->key_len = 7;
key->ext.FkType = type;
key->ext.FNum = cpu_to_be32(cnid);
key->ext.FABN = cpu_to_be16(block);
}
/*
* hfs_ext_compare()
*
* Description:
* This is the comparison function used for the extents B-tree. In
* comparing extent B-tree entries, the file id is the most
* significant field (compared as unsigned ints); the fork type is
* the second most significant field (compared as unsigned chars);
* and the allocation block number field is the least significant
* (compared as unsigned ints).
* Input Variable(s):
* struct hfs_ext_key *key1: pointer to the first key to compare
* struct hfs_ext_key *key2: pointer to the second key to compare
* Output Variable(s):
* NONE
* Returns:
* int: negative if key1<key2, positive if key1>key2, and 0 if key1==key2
* Preconditions:
* key1 and key2 point to "valid" (struct hfs_ext_key)s.
* Postconditions:
* This function has no side-effects */
int hfs_ext_keycmp(const btree_key *key1, const btree_key *key2)
{
__be32 fnum1, fnum2;
__be16 block1, block2;
fnum1 = key1->ext.FNum;
fnum2 = key2->ext.FNum;
if (fnum1 != fnum2)
return be32_to_cpu(fnum1) < be32_to_cpu(fnum2) ? -1 : 1;
if (key1->ext.FkType != key2->ext.FkType)
return key1->ext.FkType < key2->ext.FkType ? -1 : 1;
block1 = key1->ext.FABN;
block2 = key2->ext.FABN;
if (block1 == block2)
return 0;
return be16_to_cpu(block1) < be16_to_cpu(block2) ? -1 : 1;
}
/*
* hfs_ext_find_block
*
* Find a block within an extent record
*/
static u16 hfs_ext_find_block(struct hfs_extent *ext, u16 off)
{
int i;
u16 count;
for (i = 0; i < 3; ext++, i++) {
count = be16_to_cpu(ext->count);
if (off < count)
return be16_to_cpu(ext->block) + off;
off -= count;
}
/* panic? */
return 0;
}
static int hfs_ext_block_count(struct hfs_extent *ext)
{
int i;
u16 count = 0;
for (i = 0; i < 3; ext++, i++)
count += be16_to_cpu(ext->count);
return count;
}
static u16 hfs_ext_lastblock(struct hfs_extent *ext)
{
int i;
ext += 2;
for (i = 0; i < 2; ext--, i++)
if (ext->count)
break;
return be16_to_cpu(ext->block) + be16_to_cpu(ext->count);
}
static int __hfs_ext_write_extent(struct inode *inode, struct hfs_find_data *fd)
{
int res;
hfs_ext_build_key(fd->search_key, inode->i_ino, HFS_I(inode)->cached_start,
HFS_IS_RSRC(inode) ? HFS_FK_RSRC : HFS_FK_DATA);
res = hfs_brec_find(fd);
if (HFS_I(inode)->flags & HFS_FLG_EXT_NEW) {
if (res != -ENOENT)
return res;
/* Fail early and avoid ENOSPC during the btree operation */
res = hfs_bmap_reserve(fd->tree, fd->tree->depth + 1);
if (res)
return res;
hfs_brec_insert(fd, HFS_I(inode)->cached_extents, sizeof(hfs_extent_rec));
HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
} else {
if (res)
return res;
hfs_bnode_write(fd->bnode, HFS_I(inode)->cached_extents, fd->entryoffset, fd->entrylength);
HFS_I(inode)->flags &= ~HFS_FLG_EXT_DIRTY;
}
return 0;
}
int hfs_ext_write_extent(struct inode *inode)
{
struct hfs_find_data fd;
int res = 0;
if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) {
res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
if (res)
return res;
res = __hfs_ext_write_extent(inode, &fd);
hfs_find_exit(&fd);
}
return res;
}
static inline int __hfs_ext_read_extent(struct hfs_find_data *fd, struct hfs_extent *extent,
u32 cnid, u32 block, u8 type)
{
int res;
hfs_ext_build_key(fd->search_key, cnid, block, type);
fd->key->ext.FNum = 0;
res = hfs_brec_find(fd);
if (res && res != -ENOENT)
return res;
if (fd->key->ext.FNum != fd->search_key->ext.FNum ||
fd->key->ext.FkType != fd->search_key->ext.FkType)
return -ENOENT;
if (fd->entrylength != sizeof(hfs_extent_rec))
return -EIO;
hfs_bnode_read(fd->bnode, extent, fd->entryoffset, sizeof(hfs_extent_rec));
return 0;
}
static inline int __hfs_ext_cache_extent(struct hfs_find_data *fd, struct inode *inode, u32 block)
{
int res;
if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) {
res = __hfs_ext_write_extent(inode, fd);
if (res)
return res;
}
res = __hfs_ext_read_extent(fd, HFS_I(inode)->cached_extents, inode->i_ino,
block, HFS_IS_RSRC(inode) ? HFS_FK_RSRC : HFS_FK_DATA);
if (!res) {
HFS_I(inode)->cached_start = be16_to_cpu(fd->key->ext.FABN);
HFS_I(inode)->cached_blocks = hfs_ext_block_count(HFS_I(inode)->cached_extents);
} else {
HFS_I(inode)->cached_start = HFS_I(inode)->cached_blocks = 0;
HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
}
return res;
}
static int hfs_ext_read_extent(struct inode *inode, u16 block)
{
struct hfs_find_data fd;
int res;
if (block >= HFS_I(inode)->cached_start &&
block < HFS_I(inode)->cached_start + HFS_I(inode)->cached_blocks)
return 0;
res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
if (!res) {
res = __hfs_ext_cache_extent(&fd, inode, block);
hfs_find_exit(&fd);
}
return res;
}
static void hfs_dump_extent(struct hfs_extent *extent)
{
int i;
hfs_dbg(EXTENT, " ");
for (i = 0; i < 3; i++)
hfs_dbg_cont(EXTENT, " %u:%u",
be16_to_cpu(extent[i].block),
be16_to_cpu(extent[i].count));
hfs_dbg_cont(EXTENT, "\n");
}
static int hfs_add_extent(struct hfs_extent *extent, u16 offset,
u16 alloc_block, u16 block_count)
{
u16 count, start;
int i;
hfs_dump_extent(extent);
for (i = 0; i < 3; extent++, i++) {
count = be16_to_cpu(extent->count);
if (offset == count) {
start = be16_to_cpu(extent->block);
if (alloc_block != start + count) {
if (++i >= 3)
return -ENOSPC;
extent++;
extent->block = cpu_to_be16(alloc_block);
} else
block_count += count;
extent->count = cpu_to_be16(block_count);
return 0;
} else if (offset < count)
break;
offset -= count;
}
/* panic? */
return -EIO;
}
static int hfs_free_extents(struct super_block *sb, struct hfs_extent *extent,
u16 offset, u16 block_nr)
{
u16 count, start;
int i;
hfs_dump_extent(extent);
for (i = 0; i < 3; extent++, i++) {
count = be16_to_cpu(extent->count);
if (offset == count)
goto found;
else if (offset < count)
break;
offset -= count;
}
/* panic? */
return -EIO;
found:
for (;;) {
start = be16_to_cpu(extent->block);
if (count <= block_nr) {
hfs_clear_vbm_bits(sb, start, count);
extent->block = 0;
extent->count = 0;
block_nr -= count;
} else {
count -= block_nr;
hfs_clear_vbm_bits(sb, start + count, block_nr);
extent->count = cpu_to_be16(count);
block_nr = 0;
}
if (!block_nr || !i)
return 0;
i--;
extent--;
count = be16_to_cpu(extent->count);
}
}
int hfs_free_fork(struct super_block *sb, struct hfs_cat_file *file, int type)
{
struct hfs_find_data fd;
u32 total_blocks, blocks, start;
u32 cnid = be32_to_cpu(file->FlNum);
struct hfs_extent *extent;
int res, i;
if (type == HFS_FK_DATA) {
total_blocks = be32_to_cpu(file->PyLen);
extent = file->ExtRec;
} else {
total_blocks = be32_to_cpu(file->RPyLen);
extent = file->RExtRec;
}
total_blocks /= HFS_SB(sb)->alloc_blksz;
if (!total_blocks)
return 0;
blocks = 0;
for (i = 0; i < 3; i++)
blocks += be16_to_cpu(extent[i].count);
res = hfs_free_extents(sb, extent, blocks, blocks);
if (res)
return res;
if (total_blocks == blocks)
return 0;
res = hfs_find_init(HFS_SB(sb)->ext_tree, &fd);
if (res)
return res;
do {
res = __hfs_ext_read_extent(&fd, extent, cnid, total_blocks, type);
if (res)
break;
start = be16_to_cpu(fd.key->ext.FABN);
hfs_free_extents(sb, extent, total_blocks - start, total_blocks);
hfs_brec_remove(&fd);
total_blocks = start;
} while (total_blocks > blocks);
hfs_find_exit(&fd);
return res;
}
/*
* hfs_get_block
*/
int hfs_get_block(struct inode *inode, sector_t block,
struct buffer_head *bh_result, int create)
{
struct super_block *sb;
u16 dblock, ablock;
int res;
sb = inode->i_sb;
/* Convert inode block to disk allocation block */
ablock = (u32)block / HFS_SB(sb)->fs_div;
if (block >= HFS_I(inode)->fs_blocks) {
if (!create)
return 0;
if (block > HFS_I(inode)->fs_blocks)
return -EIO;
if (ablock >= HFS_I(inode)->alloc_blocks) {
res = hfs_extend_file(inode);
if (res)
return res;
}
} else
create = 0;
if (ablock < HFS_I(inode)->first_blocks) {
dblock = hfs_ext_find_block(HFS_I(inode)->first_extents, ablock);
goto done;
}
mutex_lock(&HFS_I(inode)->extents_lock);
res = hfs_ext_read_extent(inode, ablock);
if (!res)
dblock = hfs_ext_find_block(HFS_I(inode)->cached_extents,
ablock - HFS_I(inode)->cached_start);
else {
mutex_unlock(&HFS_I(inode)->extents_lock);
return -EIO;
}
mutex_unlock(&HFS_I(inode)->extents_lock);
done:
map_bh(bh_result, sb, HFS_SB(sb)->fs_start +
dblock * HFS_SB(sb)->fs_div +
(u32)block % HFS_SB(sb)->fs_div);
if (create) {
set_buffer_new(bh_result);
HFS_I(inode)->phys_size += sb->s_blocksize;
HFS_I(inode)->fs_blocks++;
inode_add_bytes(inode, sb->s_blocksize);
mark_inode_dirty(inode);
}
return 0;
}
int hfs_extend_file(struct inode *inode)
{
struct super_block *sb = inode->i_sb;
u32 start, len, goal;
int res;
mutex_lock(&HFS_I(inode)->extents_lock);
if (HFS_I(inode)->alloc_blocks == HFS_I(inode)->first_blocks)
goal = hfs_ext_lastblock(HFS_I(inode)->first_extents);
else {
res = hfs_ext_read_extent(inode, HFS_I(inode)->alloc_blocks);
if (res)
goto out;
goal = hfs_ext_lastblock(HFS_I(inode)->cached_extents);
}
len = HFS_I(inode)->clump_blocks;
start = hfs_vbm_search_free(sb, goal, &len);
if (!len) {
res = -ENOSPC;
goto out;
}
hfs_dbg(EXTENT, "extend %lu: %u,%u\n", inode->i_ino, start, len);
if (HFS_I(inode)->alloc_blocks == HFS_I(inode)->first_blocks) {
if (!HFS_I(inode)->first_blocks) {
hfs_dbg(EXTENT, "first extents\n");
/* no extents yet */
HFS_I(inode)->first_extents[0].block = cpu_to_be16(start);
HFS_I(inode)->first_extents[0].count = cpu_to_be16(len);
res = 0;
} else {
/* try to append to extents in inode */
res = hfs_add_extent(HFS_I(inode)->first_extents,
HFS_I(inode)->alloc_blocks,
start, len);
if (res == -ENOSPC)
goto insert_extent;
}
if (!res) {
hfs_dump_extent(HFS_I(inode)->first_extents);
HFS_I(inode)->first_blocks += len;
}
} else {
res = hfs_add_extent(HFS_I(inode)->cached_extents,
HFS_I(inode)->alloc_blocks -
HFS_I(inode)->cached_start,
start, len);
if (!res) {
hfs_dump_extent(HFS_I(inode)->cached_extents);
HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY;
HFS_I(inode)->cached_blocks += len;
} else if (res == -ENOSPC)
goto insert_extent;
}
out:
mutex_unlock(&HFS_I(inode)->extents_lock);
if (!res) {
HFS_I(inode)->alloc_blocks += len;
mark_inode_dirty(inode);
if (inode->i_ino < HFS_FIRSTUSER_CNID)
set_bit(HFS_FLG_ALT_MDB_DIRTY, &HFS_SB(sb)->flags);
set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
hfs_mark_mdb_dirty(sb);
}
return res;
insert_extent:
hfs_dbg(EXTENT, "insert new extent\n");
res = hfs_ext_write_extent(inode);
if (res)
goto out;
memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec));
HFS_I(inode)->cached_extents[0].block = cpu_to_be16(start);
HFS_I(inode)->cached_extents[0].count = cpu_to_be16(len);
hfs_dump_extent(HFS_I(inode)->cached_extents);
HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW;
HFS_I(inode)->cached_start = HFS_I(inode)->alloc_blocks;
HFS_I(inode)->cached_blocks = len;
res = 0;
goto out;
}
void hfs_file_truncate(struct inode *inode)
{
struct super_block *sb = inode->i_sb;
struct hfs_find_data fd;
u16 blk_cnt, alloc_cnt, start;
u32 size;
int res;
hfs_dbg(INODE, "truncate: %lu, %Lu -> %Lu\n",
inode->i_ino, (long long)HFS_I(inode)->phys_size,
inode->i_size);
if (inode->i_size > HFS_I(inode)->phys_size) {
struct address_space *mapping = inode->i_mapping;
void *fsdata;
struct page *page;
/* XXX: Can use generic_cont_expand? */
size = inode->i_size - 1;
res = pagecache_write_begin(NULL, mapping, size+1, 0, 0,
&page, &fsdata);
if (!res) {
res = pagecache_write_end(NULL, mapping, size+1, 0, 0,
page, fsdata);
}
if (res)
inode->i_size = HFS_I(inode)->phys_size;
return;
} else if (inode->i_size == HFS_I(inode)->phys_size)
return;
size = inode->i_size + HFS_SB(sb)->alloc_blksz - 1;
blk_cnt = size / HFS_SB(sb)->alloc_blksz;
alloc_cnt = HFS_I(inode)->alloc_blocks;
if (blk_cnt == alloc_cnt)
goto out;
mutex_lock(&HFS_I(inode)->extents_lock);
res = hfs_find_init(HFS_SB(sb)->ext_tree, &fd);
if (res) {
mutex_unlock(&HFS_I(inode)->extents_lock);
/* XXX: We lack error handling of hfs_file_truncate() */
return;
}
while (1) {
if (alloc_cnt == HFS_I(inode)->first_blocks) {
hfs_free_extents(sb, HFS_I(inode)->first_extents,
alloc_cnt, alloc_cnt - blk_cnt);
hfs_dump_extent(HFS_I(inode)->first_extents);
HFS_I(inode)->first_blocks = blk_cnt;
break;
}
res = __hfs_ext_cache_extent(&fd, inode, alloc_cnt);
if (res)
break;
start = HFS_I(inode)->cached_start;
hfs_free_extents(sb, HFS_I(inode)->cached_extents,
alloc_cnt - start, alloc_cnt - blk_cnt);
hfs_dump_extent(HFS_I(inode)->cached_extents);
if (blk_cnt > start) {
HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY;
break;
}
alloc_cnt = start;
HFS_I(inode)->cached_start = HFS_I(inode)->cached_blocks = 0;
HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
hfs_brec_remove(&fd);
}
hfs_find_exit(&fd);
mutex_unlock(&HFS_I(inode)->extents_lock);
HFS_I(inode)->alloc_blocks = blk_cnt;
out:
HFS_I(inode)->phys_size = inode->i_size;
HFS_I(inode)->fs_blocks = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
inode_set_bytes(inode, HFS_I(inode)->fs_blocks << sb->s_blocksize_bits);
mark_inode_dirty(inode);
}
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