deh defined as an array of type __u16[], and issue is
triggered when it's trying to access an element at
index 1, which is out of bounds because the array
has only one element at index 0.

Reported-by: syzbot+e5bb9eb00a5a5ed2a9a2@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=e5bb9eb00a5a5ed2a9a2
Signed-off-by: Bragatheswaran Manickavel <bragathemanick0908@gmail.com>
---
 fs/reiserfs/item_ops.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/reiserfs/item_ops.c b/fs/reiserfs/item_ops.c
index 3a5a752d96c7..ccf547c5e8e1 100644
--- a/fs/reiserfs/item_ops.c
+++ b/fs/reiserfs/item_ops.c
@@ -484,7 +484,7 @@ static int direntry_create_vi(struct virtual_node *vn,
 				  vn->vn_mode);
 		dir_u->entry_sizes[i] =
 		    (j ? deh_location(&deh[j - 1]) : ih_item_len(vi->vi_ih)) -
-		    deh_location(&deh[j]) + DEH_SIZE;
+		    deh_location(&deh[j - 1]) + DEH_SIZE;
 	}
 
 	size += (dir_u->entry_count * sizeof(short));
-- 
2.34.1

On 26/10/23 18:26, Bragatheswaran Manickavel wrote:
> deh defined as an array of type __u16[], and issue is
> triggered when it's trying to access an element at
> index 1, which is out of bounds because the array
> has only one element at index 0.
>
> Reported-by: syzbot+e5bb9eb00a5a5ed2a9a2@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=e5bb9eb00a5a5ed2a9a2
> Signed-off-by: Bragatheswaran Manickavel <bragathemanick0908@gmail.com>
> ---
>   fs/reiserfs/item_ops.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/reiserfs/item_ops.c b/fs/reiserfs/item_ops.c
> index 3a5a752d96c7..ccf547c5e8e1 100644
> --- a/fs/reiserfs/item_ops.c
> +++ b/fs/reiserfs/item_ops.c
> @@ -484,7 +484,7 @@ static int direntry_create_vi(struct virtual_node *vn,
>   				  vn->vn_mode);
>   		dir_u->entry_sizes[i] =
>   		    (j ? deh_location(&deh[j - 1]) : ih_item_len(vi->vi_ih)) -
> -		    deh_location(&deh[j]) + DEH_SIZE;
> +		    deh_location(&deh[j - 1]) + DEH_SIZE;
>   	}
>   
>   	size += (dir_u->entry_count * sizeof(short));

Could someone help in reviewing the changes. I see reiserfs was marked with
obsolete but still wanted to know whether this patch is correct and can be
taken (if possible)

Thanks,
Bragathe