From: Xu Rao <raoxu@uniontech.com>

fsctl_copychunk() maps errors from ksmbd_vfs_copy_file_ranges() to SMB
status codes. For -EACCES it first sets STATUS_ACCESS_DENIED, but the
following -EAGAIN test starts a separate if/else-if chain. Because
-EACCES does not match that chain, its final else immediately overwrites
the status with STATUS_UNEXPECTED_IO_ERROR.

MS-SMB2 section 3.3.5.15.6 requires FSCTL_SRV_COPYCHUNK and
FSCTL_SRV_COPYCHUNK_WRITE to fail with STATUS_ACCESS_DENIED when the
source open lacks FILE_READ_DATA or the destination open lacks
FILE_WRITE_DATA or FILE_APPEND_DATA. ksmbd_vfs_copy_file_ranges()
returns -EACCES when its source or destination access check fails, so the
current control flow reports a protocol-visible permission failure as an
unrelated I/O error.

Make the -EAGAIN condition part of the same else-if chain so the -EACCES
mapping is preserved.

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Rao <raoxu@uniontech.com>
---
 fs/smb/server/smb2pdu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index bec692bca1ca..416bf1e55c81 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -8524,7 +8524,7 @@ static int fsctl_copychunk(struct ksmbd_work *work,
 	if (ret < 0) {
 		if (ret == -EACCES)
 			rsp->hdr.Status = STATUS_ACCESS_DENIED;
-		if (ret == -EAGAIN)
+		else if (ret == -EAGAIN)
 			rsp->hdr.Status = STATUS_FILE_LOCK_CONFLICT;
 		else if (ret == -EBADF)
 			rsp->hdr.Status = STATUS_INVALID_HANDLE;
--
2.50.1

Thanks for your patch. This bug has already been fixed in the 
ksmbd-for-next-next branch:
https://github.com/smfrench/smb3-kernel/commit/35e11e324a2f97d2974ef08d308063c9c5f9e9d8

On 7/31/26 15:20, raoxu wrote:
> From: Xu Rao <raoxu@uniontech.com>
> 
> fsctl_copychunk() maps errors from ksmbd_vfs_copy_file_ranges() to SMB
> status codes. For -EACCES it first sets STATUS_ACCESS_DENIED, but the
> following -EAGAIN test starts a separate if/else-if chain. Because
> -EACCES does not match that chain, its final else immediately overwrites
> the status with STATUS_UNEXPECTED_IO_ERROR.
> 
> MS-SMB2 section 3.3.5.15.6 requires FSCTL_SRV_COPYCHUNK and
> FSCTL_SRV_COPYCHUNK_WRITE to fail with STATUS_ACCESS_DENIED when the
> source open lacks FILE_READ_DATA or the destination open lacks
> FILE_WRITE_DATA or FILE_APPEND_DATA. ksmbd_vfs_copy_file_ranges()
> returns -EACCES when its source or destination access check fails, so the
> current control flow reports a protocol-visible permission failure as an
> unrelated I/O error.
> 
> Make the -EAGAIN condition part of the same else-if chain so the -EACCES
> mapping is preserved.
> 
> Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
> Cc: stable@vger.kernel.org
> Signed-off-by: Xu Rao <raoxu@uniontech.com>
> ---
>   fs/smb/server/smb2pdu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
> index bec692bca1ca..416bf1e55c81 100644
> --- a/fs/smb/server/smb2pdu.c
> +++ b/fs/smb/server/smb2pdu.c
> @@ -8524,7 +8524,7 @@ static int fsctl_copychunk(struct ksmbd_work *work,
>   	if (ret < 0) {
>   		if (ret == -EACCES)
>   			rsp->hdr.Status = STATUS_ACCESS_DENIED;
> -		if (ret == -EAGAIN)
> +		else if (ret == -EAGAIN)
>   			rsp->hdr.Status = STATUS_FILE_LOCK_CONFLICT;
>   		else if (ret == -EBADF)
>   			rsp->hdr.Status = STATUS_INVALID_HANDLE;
> --
> 2.50.1
> 
> 

-- 
ChenXiaoSong <chenxiaosong@chenxiaosong.com>
Chinese Homepage: https://chenxiaosong.com
English Homepage: https://chenxiaosong.com/en

Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>

On 7/31/26 15:20, raoxu wrote:
> From: Xu Rao <raoxu@uniontech.com>
> 
> fsctl_copychunk() maps errors from ksmbd_vfs_copy_file_ranges() to SMB
> status codes. For -EACCES it first sets STATUS_ACCESS_DENIED, but the
> following -EAGAIN test starts a separate if/else-if chain. Because
> -EACCES does not match that chain, its final else immediately overwrites
> the status with STATUS_UNEXPECTED_IO_ERROR.
> 
> MS-SMB2 section 3.3.5.15.6 requires FSCTL_SRV_COPYCHUNK and
> FSCTL_SRV_COPYCHUNK_WRITE to fail with STATUS_ACCESS_DENIED when the
> source open lacks FILE_READ_DATA or the destination open lacks
> FILE_WRITE_DATA or FILE_APPEND_DATA. ksmbd_vfs_copy_file_ranges()
> returns -EACCES when its source or destination access check fails, so the
> current control flow reports a protocol-visible permission failure as an
> unrelated I/O error.
> 
> Make the -EAGAIN condition part of the same else-if chain so the -EACCES
> mapping is preserved.
> 
> Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
> Cc: stable@vger.kernel.org
> Signed-off-by: Xu Rao <raoxu@uniontech.com>
> ---
>   fs/smb/server/smb2pdu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
> index bec692bca1ca..416bf1e55c81 100644
> --- a/fs/smb/server/smb2pdu.c
> +++ b/fs/smb/server/smb2pdu.c
> @@ -8524,7 +8524,7 @@ static int fsctl_copychunk(struct ksmbd_work *work,
>   	if (ret < 0) {
>   		if (ret == -EACCES)
>   			rsp->hdr.Status = STATUS_ACCESS_DENIED;
> -		if (ret == -EAGAIN)
> +		else if (ret == -EAGAIN)
>   			rsp->hdr.Status = STATUS_FILE_LOCK_CONFLICT;
>   		else if (ret == -EBADF)
>   			rsp->hdr.Status = STATUS_INVALID_HANDLE;
> --
> 2.50.1
> 
> 

-- 
ChenXiaoSong <chenxiaosong@chenxiaosong.com>
Chinese Homepage: https://chenxiaosong.com
English Homepage: https://chenxiaosong.com/en