diff options
| author | Filipe Manana <fdmanana@suse.com> | 2023-01-12 14:17:20 +0000 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2023-01-16 19:46:38 +0100 |
| commit | 1f55ee6d0901d915801618bda0af4e5b937e3db7 (patch) | |
| tree | 5b586ab7e4951c99b0d65173ac3df49d856e68fc | |
| parent | 26ecf243e407be54807ad67210f7e83b9fad71ea (diff) | |
btrfs: fix invalid leaf access due to inline extent during lseek
During lseek, for SEEK_DATA and SEEK_HOLE modes, we access the disk_bytenr
of an extent without checking its type. However inline extents have their
data starting the offset of the disk_bytenr field, so accessing that field
when we have an inline extent can result in either of the following:
1) Interpret the inline extent's data as a disk_bytenr value;
2) In case the inline data is less than 8 bytes, we access part of some
other item in the leaf, or unused space in the leaf;
3) In case the inline data is less than 8 bytes and the extent item is
the first item in the leaf, we can access beyond the leaf's limit.
So fix this by not accessing the disk_bytenr field if we have an inline
extent.
Fixes: b6e833567ea1 ("btrfs: make hole and data seeking a lot more efficient")
Reported-by: Matthias Schoepfer <matthias.schoepfer@googlemail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216908
Link: https://lore.kernel.org/linux-btrfs/7f25442f-b121-2a3a-5a3d-22bcaae83cd4@leemhuis.info/
CC: stable@vger.kernel.org # 6.1
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
| -rw-r--r-- | fs/btrfs/file.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 834bbcb91102..af046d22300e 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -3541,6 +3541,7 @@ static loff_t find_desired_extent(struct file *file, loff_t offset, int whence) struct extent_buffer *leaf = path->nodes[0]; struct btrfs_file_extent_item *extent; u64 extent_end; + u8 type; if (path->slots[0] >= btrfs_header_nritems(leaf)) { ret = btrfs_next_leaf(root, path); @@ -3596,10 +3597,16 @@ static loff_t find_desired_extent(struct file *file, loff_t offset, int whence) extent = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); + type = btrfs_file_extent_type(leaf, extent); - if (btrfs_file_extent_disk_bytenr(leaf, extent) == 0 || - btrfs_file_extent_type(leaf, extent) == - BTRFS_FILE_EXTENT_PREALLOC) { + /* + * Can't access the extent's disk_bytenr field if this is an + * inline extent, since at that offset, it's where the extent + * data starts. + */ + if (type == BTRFS_FILE_EXTENT_PREALLOC || + (type == BTRFS_FILE_EXTENT_REG && + btrfs_file_extent_disk_bytenr(leaf, extent) == 0)) { /* * Explicit hole or prealloc extent, search for delalloc. * A prealloc extent is treated like a hole. |