On 05/14/2018 03:03 PM, Qu Wenruo wrote:
> There is one report of compressed extent happens in btrfs, but has no
> csum and then leads to possible decompress error screwing up kernel
> memory.
>
> Although it's a kernel bug, and won't cause problem until compressed
> data get corrupted, let's catch such problem in advance.
>
> This patch will catch any unexpected compressed extent with:
>
> 1) 0 or less than expected csum
>
> 2) nodatasum flag set in the inode item
>
> This is for lowmem mode.
>
> Reported-by: James Harvey <jamespharvey20@xxxxxxxxx>
> Issue: #134
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
Reviewed-by: Su Yue <suy.fnst@xxxxxxxxxxxxxx>
> ---
> check/mode-lowmem.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c
> index dac3201b7d99..8e6d5e8de12a 100644
> --- a/check/mode-lowmem.c
> +++ b/check/mode-lowmem.c
> @@ -1543,6 +1543,24 @@ static int check_file_extent(struct btrfs_root *root, struct btrfs_key *fkey,
> csum_found);
> }
> }
> + /*
> + * Extra check for compressed extents.
> + * Btrfs doesn't allow NODATASUM and compressed extent co-exist, thus
> + * all compressed extent should have csum.
> + */
> + if (compressed && csum_found < search_len) {
> + error(
> +"root %llu EXTENT_DATA[%llu %llu] compressed extent must have csum, but only %llu bytes has csum, expect %llu",
> + root->objectid, fkey->objectid, fkey->offset, csum_found,
> + search_len);
> + err |= CSUM_ITEM_MISSING;
> + }
> + if (compressed && nodatasum) {
> + error(
> +"root %llu EXTENT_DATA[%llu %llu] is compressed, but inode flag doesn't allow it",
> + root->objectid, fkey->objectid, fkey->offset);
> + err |= FILE_EXTENT_ERROR;
> + }
>
> /* Check EXTENT_DATA hole */
> if (!no_holes && *end != fkey->offset) {
>
Attachment:
pEpkey.asc
Description: application/pgp-keys
