Re: [PATCH] Null check to prevent null-ptr-deref bug

Greg KH
2023-05-28T16:50:44Z

On Sun, May 28, 2023 at 09:44:00AM -0700, Prince Kumar Maurya wrote:
> sb_getblk(inode->i_sb, parent) return a null ptr and taking lock on that leads to the null-ptr-deref bug.
>
> Signed-off-by: Prince Kumar Maurya <princekumarmaurya06@gmail.com>
> ---
> fs/sysv/itree.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/sysv/itree.c b/fs/sysv/itree.c
> index b22764fe669c..3a6b66e719fd 100644
> --- a/fs/sysv/itree.c
> +++ b/fs/sysv/itree.c
> @@ -145,6 +145,8 @@ static int alloc_branch(struct inode *inode,
> */
> parent = block_to_cpu(SYSV_SB(inode->i_sb), branch[n-1].key);
> bh = sb_getblk(inode->i_sb, parent);
> + if (!bh)
> + break;
> lock_buffer(bh);
> memset(bh->b_data, 0, blocksize);
> branch[n].bh = bh;
> --
> 2.40.1

Why resend this when I already responded:
https://lore.kernel.org/r/2023052803-pucker-depress-5452@gregkh

confused,

greg k-h