Commit dac7a4b4 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: lock the xattr block before checksuming it

We must lock the xattr block before calculating or verifying the
checksum in order to avoid spurious checksum failures.

https://bugzilla.kernel.org/show_bug.cgi?id=193661



Reported-by: default avatarColin Ian King <colin.king@canonical.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
parent cd9cb405
......@@ -131,31 +131,26 @@ static __le32 ext4_xattr_block_csum(struct inode *inode,
}
static int ext4_xattr_block_csum_verify(struct inode *inode,
sector_t block_nr,
struct ext4_xattr_header *hdr)
struct buffer_head *bh)
{
if (ext4_has_metadata_csum(inode->i_sb) &&
(hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr)))
return 0;
return 1;
}
static void ext4_xattr_block_csum_set(struct inode *inode,
sector_t block_nr,
struct ext4_xattr_header *hdr)
{
if (!ext4_has_metadata_csum(inode->i_sb))
return;
struct ext4_xattr_header *hdr = BHDR(bh);
int ret = 1;
hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr);
if (ext4_has_metadata_csum(inode->i_sb)) {
lock_buffer(bh);
ret = (hdr->h_checksum == ext4_xattr_block_csum(inode,
bh->b_blocknr, hdr));
unlock_buffer(bh);
}
return ret;
}
static inline int ext4_handle_dirty_xattr_block(handle_t *handle,
struct inode *inode,
struct buffer_head *bh)
static void ext4_xattr_block_csum_set(struct inode *inode,
struct buffer_head *bh)
{
ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh));
return ext4_handle_dirty_metadata(handle, inode, bh);
if (ext4_has_metadata_csum(inode->i_sb))
BHDR(bh)->h_checksum = ext4_xattr_block_csum(inode,
bh->b_blocknr, BHDR(bh));
}
static inline const struct xattr_handler *
......@@ -233,7 +228,7 @@ ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)
if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
BHDR(bh)->h_blocks != cpu_to_le32(1))
return -EFSCORRUPTED;
if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
if (!ext4_xattr_block_csum_verify(inode, bh))
return -EFSBADCRC;
error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size,
bh->b_data);
......@@ -618,23 +613,22 @@ ext4_xattr_release_block(handle_t *handle, struct inode *inode,
}
}
ext4_xattr_block_csum_set(inode, bh);
/*
* Beware of this ugliness: Releasing of xattr block references
* from different inodes can race and so we have to protect
* from a race where someone else frees the block (and releases
* its journal_head) before we are done dirtying the buffer. In
* nojournal mode this race is harmless and we actually cannot
* call ext4_handle_dirty_xattr_block() with locked buffer as
* call ext4_handle_dirty_metadata() with locked buffer as
* that function can call sync_dirty_buffer() so for that case
* we handle the dirtying after unlocking the buffer.
*/
if (ext4_handle_valid(handle))
error = ext4_handle_dirty_xattr_block(handle, inode,
bh);
error = ext4_handle_dirty_metadata(handle, inode, bh);
unlock_buffer(bh);
if (!ext4_handle_valid(handle))
error = ext4_handle_dirty_xattr_block(handle, inode,
bh);
error = ext4_handle_dirty_metadata(handle, inode, bh);
if (IS_SYNC(inode))
ext4_handle_sync(handle);
dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
......@@ -863,13 +857,14 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
ext4_xattr_cache_insert(ext4_mb_cache,
bs->bh);
}
ext4_xattr_block_csum_set(inode, bs->bh);
unlock_buffer(bs->bh);
if (error == -EFSCORRUPTED)
goto bad_block;
if (!error)
error = ext4_handle_dirty_xattr_block(handle,
inode,
bs->bh);
error = ext4_handle_dirty_metadata(handle,
inode,
bs->bh);
if (error)
goto cleanup;
goto inserted;
......@@ -967,10 +962,11 @@ inserted:
ce->e_reusable = 0;
ea_bdebug(new_bh, "reusing; refcount now=%d",
ref);
ext4_xattr_block_csum_set(inode, new_bh);
unlock_buffer(new_bh);
error = ext4_handle_dirty_xattr_block(handle,
inode,
new_bh);
error = ext4_handle_dirty_metadata(handle,
inode,
new_bh);
if (error)
goto cleanup_dquot;
}
......@@ -1020,11 +1016,12 @@ getblk_failed:
goto getblk_failed;
}
memcpy(new_bh->b_data, s->base, new_bh->b_size);
ext4_xattr_block_csum_set(inode, new_bh);
set_buffer_uptodate(new_bh);
unlock_buffer(new_bh);
ext4_xattr_cache_insert(ext4_mb_cache, new_bh);
error = ext4_handle_dirty_xattr_block(handle,
inode, new_bh);
error = ext4_handle_dirty_metadata(handle, inode,
new_bh);
if (error)
goto cleanup;
}
......
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