[PATCH] ubifs: Allocate shash export state on stack

[Zhihao Cheng]

在 2025/6/20 11:45, Herbert Xu 写道:
> The output size of crypto_shash_export should be obtained via
> crypto_shash_statesize and not crypto_shash_descsize.  The latter
> could be too small (but is usually big enough).
> 
> However, as state sizes are API-limited, simply allocate it on the
> stack.
> 
> Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
> 

Reviewed-by: Zhihao Cheng <chengzhihao1 at huawei.com>

Maybe adding a fix tag is better, commit 49525e5eecca5e1("ubifs: Add 
helper functions for authentication support").

> diff --git a/fs/ubifs/auth.c b/fs/ubifs/auth.c
> index a4a0158f712d..edf012aa51bf 100644
> --- a/fs/ubifs/auth.c
> +++ b/fs/ubifs/auth.c
> @@ -474,13 +474,9 @@ int __ubifs_node_verify_hmac(const struct ubifs_info *c, const void *node,
>   int __ubifs_shash_copy_state(const struct ubifs_info *c, struct shash_desc *src,
>   			     struct shash_desc *target)
>   {
> -	u8 *state;
> +	u8 state[HASH_MAX_STATESIZE];
>   	int err;
>   
> -	state = kmalloc(crypto_shash_descsize(src->tfm), GFP_NOFS);
> -	if (!state)
> -		return -ENOMEM;
> -
>   	err = crypto_shash_export(src, state);
>   	if (err)
>   		goto out;
> @@ -488,8 +484,6 @@ int __ubifs_shash_copy_state(const struct ubifs_info *c, struct shash_desc *src,
>   	err = crypto_shash_import(target, state);
>   
>   out:
> -	kfree(state);
> -
>   	return err;
>   }
>   
>