Re: [PATCH 8/8] erofs-utils: fix read error and short read handling

[Gao Xiang <xiang@kernel.org>]

On Thu, Nov 12, 2026 at 08:47:25PM +0800, Yifan Zhao wrote:
> Several erofs_io_read() and erofs_io_pread() callers mishandle negative
> errors or unexpected short reads, potentially reporting success or
> looping at EOF.
> 
> Propagate negative errors, reject unexpected short reads and premature
> EOF, and preserve the result reported by the ublk handler.
> 
> Also cap OCI blob copies at the requested length.
> 
> Assisted-by: Codex:gpt-6-astra
> Assisted-by: Claude Code:deepseek-v4.1-flash-1017
> Signed-off-by: Yifan Zhao <stopire@gmail.com>
> ---
>  lib/backends/fanotify.c |  3 ++-
>  lib/backends/nbd.c      |  2 ++
>  lib/backends/ublk.c     |  2 +-
>  lib/compress.c          |  2 +-
>  lib/fragments.c         |  2 +-
>  lib/inode.c             | 11 +++++------
>  lib/remotes/oci.c       |  1 +
>  lib/super.c             |  2 +-
>  mount/main.c            | 10 +++++-----
>  9 files changed, 19 insertions(+), 16 deletions(-)
> 
> diff --git a/lib/backends/fanotify.c b/lib/backends/fanotify.c
> index cf8b616..898ea84 100644
> --- a/lib/backends/fanotify.c
> +++ b/lib/backends/fanotify.c
> @@ -169,7 +169,8 @@ static int erofs_fanotify_handle_range(struct erofs_fanotify_ctx *ctx,
>  		  (unsigned long long)(offset + length));
>  
>  	read_len = erofs_io_pread(&ctx->vd, ctx->fetch_buf, length, offset);
> -	if (read_len < 0) {
> +	if (read_len != length) {
> +		read_len = read_len < 0 ? read_len : -EIO;
>  		erofs_err("Failed to fetch range [%llu, %llu): %s",
>  			  (unsigned long long)offset,
>  			  (unsigned long long)(offset + length),
> diff --git a/lib/backends/nbd.c b/lib/backends/nbd.c
> index db0df44..81506b1 100644
> --- a/lib/backends/nbd.c
> +++ b/lib/backends/nbd.c
> @@ -600,6 +600,8 @@ int erofs_nbd_get_request(int skfd, struct erofs_nbd_request *rq)
>  	int err;
>  
>  	err = erofs_io_read(&vf, rq, sizeof(*rq));
> +	if (err < 0)
> +		return err;
>  	if (err < sizeof(*rq))
>  		return -EPIPE;
>  
> diff --git a/lib/backends/ublk.c b/lib/backends/ublk.c
> index d2c5e19..7fa88d9 100644
> --- a/lib/backends/ublk.c
> +++ b/lib/backends/ublk.c
> @@ -630,7 +630,7 @@ static int ublk_handle_io(struct erofs_ublk_queue *q, int tag)
>  		if (ret < 0)
>  			io->result = ret;
>  		else
> -			io->result = req.nr_sectors << 9;
> +			io->result = req.result;

I don't apply this one, because I think there are two many changes
related to different interfaces.

especially this one, I don't know what happens just according to
the code here.

Could you just split this into multiple patch, each patch address one
interface, like erofs_io_pread()... etc.

I applied the remaining ones, so next time just resend these two.

Thanks,
Gao Xiang