linux-kernel - Re: [PATCH] jfs: validate max amount of blocks before allocation.

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Date:   Sun, 23 Jul 2023 14:06:30 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Aleksei Filippov <halip0503@...il.com>
Cc:     jfs-discussion@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        shaggy@...nel.org,
        syzbot+5f088f29593e6b4c8db8@...kaller.appspotmail.com
Subject: Re: [PATCH] jfs: validate max amount of blocks before allocation.

On Sun, Jul 23, 2023 at 03:02:09PM +0300, Aleksei Filippov wrote:
> From: Alexei Filippov <halip0503@...il.com>
> 
> The lack of checking bmp->db_max_freebud in extBalloc() can lead to
> shift out of bounds, so this patch prevents undefined behavior, because
> bmp->db_max_freebud == -1 only if there is no free space.
> 
> Signed-off-by: Aleksei Filippov <halip0503@...il.com>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Reported-and-tested-by: syzbot+5f088f29593e6b4c8db8@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?id=01abadbd6ae6a08b1f1987aa61554c6b3ac19ff2
> ---
>  fs/jfs/jfs_extent.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/fs/jfs/jfs_extent.c b/fs/jfs/jfs_extent.c
> index ae99a7e232ee..a82751e6c47f 100644
> --- a/fs/jfs/jfs_extent.c
> +++ b/fs/jfs/jfs_extent.c
> @@ -311,6 +311,11 @@ extBalloc(struct inode *ip, s64 hint, s64 * nblocks, s64 * blkno)
>  	 * blocks in the map. in that case, we'll start off with the
>  	 * maximum free.
>  	 */
> +
> +	/* give up if no space left */
> +	if (bmp->db_maxfreebud == -1)
> +		return -ENOSPC;
> +
>  	max = (s64) 1 << bmp->db_maxfreebud;
>  	if (*nblocks >= max && *nblocks > nbperpage)
>  		nb = nblks = (max > nbperpage) ? max : nbperpage;
> -- 
> 2.25.1
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- This looks like a new version of a previously submitted patch, but you
  did not list below the --- line any changes from the previous version.
  Please read the section entitled "The canonical patch format" in the
  kernel file, Documentation/process/submitting-patches.rst for what
  needs to be done here to properly describe this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot