[PATCH v2] dm verity: fix error handling for check_at_most_once on FEC

[PATCH v2] dm verity: fix error handling for check_at_most_once on FEC

[Yeongjin Gil]

In verity_end_io(), if bi_status is not BLK_STS_OK, it can be return
directly. But if FEC configured, it is desired to correct the data page
through verity_verify_io. And the return value will be converted to
blk_status and passed to verity_finish_io().

BTW, when a bit is set in v->validated_blocks, verity_verify_io() skips
verification regardless of I/O error for the corresponding bio. In this
case, the I/O error could not be returned properly, and as a result,
there is a problem that abnormal data could be read for the
corresponding block.

To fix this problem, when an I/O error occurs, do not skip verification
even if the bit related is set in v->validated_blocks.

Fixes: 843f38d382b1 ("dm verity: add 'check_at_most_once' option to only validate hashes once")
Cc: stable@vger.kernel.org
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Yeongjin Gil <youngjin.gil@samsung.com>
---
v2:
-change commit message and tag
---
 drivers/md/dm-verity-target.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index ade83ef3b439..9316399b920e 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -523,7 +523,7 @@ static int verity_verify_io(struct dm_verity_io *io)
 		sector_t cur_block = io->block + b;
 		struct ahash_request *req = verity_io_hash_req(v, io);
 
-		if (v->validated_blocks &&
+		if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
 		    likely(test_bit(cur_block, v->validated_blocks))) {
 			verity_bv_skip_block(v, io, iter);
 			continue;
-- 
2.40.0

Re: [PATCH v2] dm verity: fix error handling for check_at_most_once on FEC

[Eric Biggers]

On Mon, Mar 20, 2023 at 03:59:32PM +0900, Yeongjin Gil wrote:
> In verity_end_io(), if bi_status is not BLK_STS_OK, it can be return
> directly. But if FEC configured, it is desired to correct the data page
> through verity_verify_io. And the return value will be converted to
> blk_status and passed to verity_finish_io().
> 
> BTW, when a bit is set in v->validated_blocks, verity_verify_io() skips
> verification regardless of I/O error for the corresponding bio. In this
> case, the I/O error could not be returned properly, and as a result,
> there is a problem that abnormal data could be read for the
> corresponding block.
> 
> To fix this problem, when an I/O error occurs, do not skip verification
> even if the bit related is set in v->validated_blocks.
> 
> Fixes: 843f38d382b1 ("dm verity: add 'check_at_most_once' option to only validate hashes once")
> Cc: stable@vger.kernel.org
> Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
> Signed-off-by: Yeongjin Gil <youngjin.gil@samsung.com>
> ---
> v2:
> -change commit message and tag
> ---
>  drivers/md/dm-verity-target.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
> index ade83ef3b439..9316399b920e 100644
> --- a/drivers/md/dm-verity-target.c
> +++ b/drivers/md/dm-verity-target.c
> @@ -523,7 +523,7 @@ static int verity_verify_io(struct dm_verity_io *io)
>  		sector_t cur_block = io->block + b;
>  		struct ahash_request *req = verity_io_hash_req(v, io);
>  
> -		if (v->validated_blocks &&
> +		if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
>  		    likely(test_bit(cur_block, v->validated_blocks))) {
>  			verity_bv_skip_block(v, io, iter);
>  			continue;
> -- 

Looks good now, thanks!

Reviewed-by: Eric Biggers <ebiggers@google.com>

- Eric