2024-01-18 14:16:49

by Markus Elfring

Subject: [PATCH] pstore/ram_core: Improve exception handling in persistent_ram_new()

From: Markus Elfring <[email protected]>
Date: Thu, 18 Jan 2024 14:57:21 +0100

* Omit an initialisation (for the variable “ret”)
which became unnecessary with this refactoring
because a memory allocation failure will be directly indicated
by a corresponding return statement in an if branch.

* Move a call of the function “kstrdup” before two other statements.

Signed-off-by: Markus Elfring <[email protected]>
---
fs/pstore/ram_core.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index f1848cdd6d34..5047a8502e17 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -586,21 +586,23 @@ struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
unsigned int memtype, u32 flags, char *label)
{
struct persistent_ram_zone *prz;
- int ret = -ENOMEM;
+ int ret;

prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
if (!prz) {
pr_err("failed to allocate persistent ram zone\n");
- goto err;
+ return ERR_PTR(-ENOMEM);
+ }
+
+ prz->label = kstrdup(label, GFP_KERNEL);
+ if (!prz->label) {
+ kfree(prz);
+ return ERR_PTR(-ENOMEM);
}

/* Initialize general buffer state. */
raw_spin_lock_init(&prz->buffer_lock);
prz->flags = flags;
- prz->label = kstrdup(label, GFP_KERNEL);
- if (!prz->label)
- goto err;
-
ret = persistent_ram_buffer_map(start, size, prz, memtype);
if (ret)
goto err;
--
2.43.0

2024-02-01 18:43:16

by Kees Cook

Subject: Re: [PATCH] pstore/ram_core: Improve exception handling in persistent_ram_new()

On Thu, Jan 18, 2024 at 03:06:53PM +0100, Markus Elfring wrote:
> From: Markus Elfring <[email protected]>
> Date: Thu, 18 Jan 2024 14:57:21 +0100
>
> * Omit an initialisation (for the variable “ret”)
> which became unnecessary with this refactoring
> because a memory allocation failure will be directly indicated
> by a corresponding return statement in an if branch.
>
> * Move a call of the function “kstrdup” before two other statements.
>
> Signed-off-by: Markus Elfring <[email protected]>

Thanks for you patch!

I've decided not to apply it because I prefer having a single exit path
for error handling, and it works as-is already.

-Kees

> ---
> fs/pstore/ram_core.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
> index f1848cdd6d34..5047a8502e17 100644
> --- a/fs/pstore/ram_core.c
> +++ b/fs/pstore/ram_core.c
> @@ -586,21 +586,23 @@ struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
> unsigned int memtype, u32 flags, char *label)
> {
> struct persistent_ram_zone *prz;
> - int ret = -ENOMEM;
> + int ret;
>
> prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
> if (!prz) {
> pr_err("failed to allocate persistent ram zone\n");
> - goto err;
> + return ERR_PTR(-ENOMEM);
> + }
> +
> + prz->label = kstrdup(label, GFP_KERNEL);
> + if (!prz->label) {
> + kfree(prz);
> + return ERR_PTR(-ENOMEM);
> }
>
> /* Initialize general buffer state. */
> raw_spin_lock_init(&prz->buffer_lock);
> prz->flags = flags;
> - prz->label = kstrdup(label, GFP_KERNEL);
> - if (!prz->label)
> - goto err;
> -
> ret = persistent_ram_buffer_map(start, size, prz, memtype);
> if (ret)
> goto err;
> --
> 2.43.0
>

--
Kees Cook