linux-kernel - Re: [PATCH] jfs : fix shift-out-of-bounds in dbUpdatePMap

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Date:   Tue, 29 Aug 2023 12:49:42 -0500
From:   Dave Kleikamp <dave.kleikamp@...cle.com>
To:     Manas Ghandat <ghandatmanas@...il.com>, liushixin2@...wei.com
Cc:     jfs-discussion@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        Linux-kernel-mentees@...ts.linuxfoundation.org,
        syzbot+91ad2b52815a08caf4ea@...kaller.appspotmail.com
Subject: Re: [PATCH] jfs : fix shift-out-of-bounds in dbUpdatePMap

On 8/27/23 12:05AM, Manas Ghandat wrote:
> Currently there is no bound check for number of logical blocks per
> page (bmp->db_l2nbperpage). Added the required bound check for the
> calculation of dmap.

This should already be fixed by 11509910c599 ("jfs: jfs_dmap: Validate 
db_l2nbperpage while mounting")

Can you please verify if this problem still exists in v6.5?

Shaggy

> 
> Reported-by: syzbot+91ad2b52815a08caf4ea@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=91ad2b52815a08caf4ea
> Fixes: 4d81715fc5df ("[PATCH] fs/jfs: Conversion to generic boolean")
> Signed-off-by: Manas Ghandat <ghandatmanas@...il.com>
> ---
>   fs/jfs/jfs_dmap.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
> index a3eb1e826947..6a5df296fdc8 100644
> --- a/fs/jfs/jfs_dmap.c
> +++ b/fs/jfs/jfs_dmap.c
> @@ -467,6 +467,10 @@ dbUpdatePMap(struct inode *ipbmap,
>   	lastlblkno = 0;
>   	for (rem = nblocks; rem > 0; rem -= nblks, blkno += nblks) {
>   		/* get the buffer for the current dmap. */
> +
> +		if (bmp->db_l2nbperpage > L2BPERDMAP)
> +			return -EIO;
> +
>   		lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
>   		if (lblkno != lastlblkno) {
>   			if (mp) {