[PATCH] RAS/AMD/ATL: Fix bit overflow in denorm_addr_df4_np2()

[PATCH] RAS/AMD/ATL: Fix bit overflow in denorm_addr_df4_np2()

[Yazen Ghannam]

The hash_pa8 and hashed_bit values in denorm_addr_df4_np2() are
currently defined as u8 types. These variables represent single bits.

'hash_pa8' is set based on logical AND operations using masks with more
than 8 bits. So the calculated value will not fit in this variable. It
will always be '0'. The 'hash_pa8' check later in the function will fail
which produces incorrect results for some cases.

Change these variables to bool type. This clarifies that they are
single bit values. Also, this allows the compiler to ensure they hold
the proper results. Remove an unnecessary shift operation.

Fixes: 3f3174996be6 ("RAS: Introduce AMD Address Translation Library")
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---
 drivers/ras/amd/atl/denormalize.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/ras/amd/atl/denormalize.c b/drivers/ras/amd/atl/denormalize.c
index 49a900e066f1..f46bce119255 100644
--- a/drivers/ras/amd/atl/denormalize.c
+++ b/drivers/ras/amd/atl/denormalize.c
@@ -545,7 +545,7 @@ static int denorm_addr_df4_np2(struct addr_ctx *ctx)
 	unsigned int mod_value, shift_value;
 	u16 mask = df_cfg.component_id_mask;
 	u64 temp_addr_a, temp_addr_b;
-	u8 hash_pa8, hashed_bit;
+	bool hash_pa8, hashed_bit;
 
 	switch (ctx->map.intlv_mode) {
 	case DF4_NPS4_3CHAN_HASH:
@@ -578,7 +578,6 @@ static int denorm_addr_df4_np2(struct addr_ctx *ctx)
 		temp_addr_a	= remove_bits(shift_value, shift_value, ctx->ret_addr);
 	} else {
 		hash_pa8	= (ctx->coh_st_fabric_id & df_cfg.socket_id_mask);
-		hash_pa8	>>= df_cfg.socket_id_shift;
 		temp_addr_a	= ctx->ret_addr;
 	}
 
-- 
2.34.1

Re: [PATCH] RAS/AMD/ATL: Fix bit overflow in denorm_addr_df4_np2()

[Borislav Petkov]

On Thu, Feb 22, 2024 at 10:54:49AM -0600, Yazen Ghannam wrote:
> The hash_pa8 and hashed_bit values in denorm_addr_df4_np2() are
> currently defined as u8 types. These variables represent single bits.
> 
> 'hash_pa8' is set based on logical AND operations using masks with more
> than 8 bits. So the calculated value will not fit in this variable. It
> will always be '0'. The 'hash_pa8' check later in the function will fail
> which produces incorrect results for some cases.
> 
> Change these variables to bool type. This clarifies that they are
> single bit values. Also, this allows the compiler to ensure they hold
> the proper results. Remove an unnecessary shift operation.
> 
> Fixes: 3f3174996be6 ("RAS: Introduce AMD Address Translation Library")
> Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
> ---
>  drivers/ras/amd/atl/denormalize.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/ras/amd/atl/denormalize.c b/drivers/ras/amd/atl/denormalize.c
> index 49a900e066f1..f46bce119255 100644
> --- a/drivers/ras/amd/atl/denormalize.c
> +++ b/drivers/ras/amd/atl/denormalize.c
> @@ -545,7 +545,7 @@ static int denorm_addr_df4_np2(struct addr_ctx *ctx)
>  	unsigned int mod_value, shift_value;
>  	u16 mask = df_cfg.component_id_mask;
>  	u64 temp_addr_a, temp_addr_b;
> -	u8 hash_pa8, hashed_bit;
> +	bool hash_pa8, hashed_bit;
>  
>  	switch (ctx->map.intlv_mode) {
>  	case DF4_NPS4_3CHAN_HASH:
> @@ -578,7 +578,6 @@ static int denorm_addr_df4_np2(struct addr_ctx *ctx)
>  		temp_addr_a	= remove_bits(shift_value, shift_value, ctx->ret_addr);
>  	} else {
>  		hash_pa8	= (ctx->coh_st_fabric_id & df_cfg.socket_id_mask);
> -		hash_pa8	>>= df_cfg.socket_id_shift;
>  		temp_addr_a	= ctx->ret_addr;
>  	}
>  
> -- 

Applied, thanks.

-- 
Regards/Gruss,
    Boris.

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