Re: [PATCH] jfs: fix array-index-out-of-bounds in diAlloc

[Dave Kleikamp]

On 9/26/23 2:13AM, Manas Ghandat wrote:
> Currently there is not check against the agno of the iag while
> allocating new inodes to avoid fragmentation problem. Added the check
> which is required.

Does this fix an observed problem? It seems reasonable and if we add 
this we may also want to make sure that agno doesn't exceed db_numag,
(JFS_SBI(pip->i_sb)->bmap->db_numag) (yuck).

> Signed-off-by: Manas Ghandat <ghandatmanas@xxxxxxxxx>
> ---
>   fs/jfs/jfs_imap.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
> index 799d3837e7c2..ace8a1506380 100644
> --- a/fs/jfs/jfs_imap.c
> +++ b/fs/jfs/jfs_imap.c
> @@ -1355,6 +1355,8 @@ int diAlloc(struct inode *pip, bool dir, struct inode *ip)
>   
>   	/* get the ag number of this iag */
>   	agno = BLKTOAG(JFS_IP(pip)->agstart, JFS_SBI(pip->i_sb));
> +	if (agno < 0)
> +		return -EIO;
>   
>   	if (atomic_read(&JFS_SBI(pip->i_sb)->bmap->db_active[agno])) {
>   		/*