Re: [PATCH v2 08/10] hash: fix unaligned access in predictable RSS

[Bruce Richardson <bruce.richardson@intel.com>]

On Mon, Jun 23, 2025 at 03:52:38PM +0200, David Marchand wrote:
> Caught by UBSan:
> 
> ../lib/hash/rte_thash.c:421:8: runtime error: load of misaligned address
> 	0x0001816c2da3 for type 'uint32_t' (aka 'unsigned int'),
> 	which requires 4 byte alignment
> 
> Fixes: 28ebff11c2dc ("hash: add predictable RSS")
> Cc: stable@dpdk.org
> 
> Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
>  lib/hash/rte_thash.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/hash/rte_thash.c b/lib/hash/rte_thash.c
> index 6c662bf14f..6d4dbea6d7 100644
> --- a/lib/hash/rte_thash.c
> +++ b/lib/hash/rte_thash.c
> @@ -415,10 +415,10 @@ generate_subkey(struct rte_thash_ctx *ctx, struct thash_lfsr *lfsr,
>  static inline uint32_t
>  get_subvalue(struct rte_thash_ctx *ctx, uint32_t offset)
>  {
> -	uint32_t *tmp, val;
> +	uint32_t tmp, val;
>  
> -	tmp = (uint32_t *)(&ctx->hash_key[offset >> 3]);
> -	val = rte_be_to_cpu_32(*tmp);
> +	memcpy(&tmp, &ctx->hash_key[offset >> 3], sizeof(tmp));
> +	val = rte_be_to_cpu_32(tmp);
>  	val >>= (TOEPLITZ_HASH_LEN - ((offset & (CHAR_BIT - 1)) +
>  		ctx->reta_sz_log));
>  
> -- 
> 2.49.0
>