[PATCH v1] fs: proc: Add error checking for d_hash_and_lookup()

[PATCH v1] fs: proc: Add error checking for d_hash_and_lookup()

[Wang Ming]

In case of failure, d_hash_and_lookup() returns NULL or an error
pointer. The proc_fill_cache() needs to add the handling of the
error pointer returned by d_hash_and_lookup().

Signed-off-by: Wang Ming <machel@vivo.com>
---
 fs/proc/base.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index bbc998fd2a2f..4c0e8329b318 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2071,6 +2071,8 @@ bool proc_fill_cache(struct file *file, struct dir_context *ctx,
 	ino_t ino = 1;
 
 	child = d_hash_and_lookup(dir, &qname);
+	if (IS_ERR(child))
+		goto end_instantiate;
 	if (!child) {
 		DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
 		child = d_alloc_parallel(dir, &qname, &wq);
-- 
2.25.1

Re: [PATCH v1] fs: proc: Add error checking for d_hash_and_lookup()

[Christian Brauner]

On Thu, Jul 13, 2023 at 07:32:48PM +0800, Wang Ming wrote:
> In case of failure, d_hash_and_lookup() returns NULL or an error
> pointer. The proc_fill_cache() needs to add the handling of the
> error pointer returned by d_hash_and_lookup().
> 
> Signed-off-by: Wang Ming <machel@vivo.com>
> ---
>  fs/proc/base.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index bbc998fd2a2f..4c0e8329b318 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2071,6 +2071,8 @@ bool proc_fill_cache(struct file *file, struct dir_context *ctx,
>  	ino_t ino = 1;
>  
>  	child = d_hash_and_lookup(dir, &qname);
> +	if (IS_ERR(child))
> +		goto end_instantiate;

As procfs doesn't have a separate dentry hash function this doesn't make
much sense. It will always be either NULL or valid.