Re: [PATCH 10/10] staging: lustre: fix error deref in ll_splice_alias().

From: James Simmons
Date: Tue May 01 2018 - 23:06:05 EST



> d_splice_alias() can return an ERR_PTR().
> If it does while debugging is enabled, the following
> CDEBUG() will dereference that error and crash.
>
> So add appropriate checking, and provide a separate
> debug message for the error case.

Yeah!!! It fixed the issues. Thank you.

Reviewed-by: James Simmons <jsimmons@xxxxxxxxxxxxx>

> Reported-by: James Simmons <jsimmons@xxxxxxxxxxxxx>
> Fixes: e9d4f0b9f559 ("staging: lustre: llite: use d_splice_alias for directories.")
> Signed-off-by: NeilBrown <neilb@xxxxxxxx>
> ---
> drivers/staging/lustre/lustre/llite/namei.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/lustre/lustre/llite/namei.c b/drivers/staging/lustre/lustre/llite/namei.c
> index 6c9ec462eb41..24a6873d86a2 100644
> --- a/drivers/staging/lustre/lustre/llite/namei.c
> +++ b/drivers/staging/lustre/lustre/llite/namei.c
> @@ -442,11 +442,15 @@ struct dentry *ll_splice_alias(struct inode *inode, struct dentry *de)
> } else {
> struct dentry *new = d_splice_alias(inode, de);
>
> + if (IS_ERR(new))
> + CDEBUG(D_DENTRY, "splice inode %p as %pd gives error %lu\n",
> + inode, de, PTR_ERR(new));
> if (new)
> de = new;
> }
> - CDEBUG(D_DENTRY, "Add dentry %p inode %p refc %d flags %#x\n",
> - de, d_inode(de), d_count(de), de->d_flags);
> + if (!IS_ERR(de))
> + CDEBUG(D_DENTRY, "Add dentry %p inode %p refc %d flags %#x\n",
> + de, d_inode(de), d_count(de), de->d_flags);
> return de;
> }
>
>
>
>