linux-kernel - Re: [PATCH] net/mlx4_core: Avoid impossible mlx4_db

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <3biiqfwwvlbkvo5tx56nmcl4rzbq5w7u3kxn5f5ctwsolxpubo@isskxigmypwz>
Date: Mon, 10 Feb 2025 16:01:10 -0800
From: Justin Stitt <justinstitt@...gle.com>
To: Kees Cook <kees@...nel.org>
Cc: Tariq Toukan <tariqt@...dia.com>, Andrew Lunn <andrew+netdev@...n.ch>, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Yishai Hadas <yishaih@...dia.com>, netdev@...r.kernel.org, linux-rdma@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] net/mlx4_core: Avoid impossible mlx4_db_alloc() order
 value

On Mon, Feb 10, 2025 at 09:45:05AM -0800, Kees Cook wrote:
> GCC can see that the value range for "order" is capped, but this leads
> it to consider that it might be negative, leading to a false positive
> warning (with GCC 15 with -Warray-bounds -fdiagnostics-details):
> 
> ../drivers/net/ethernet/mellanox/mlx4/alloc.c:691:47: error: array subscript -1 is below array bounds of 'long unsigned int *[2]' [-Werror=array-bounds=]
>   691 |                 i = find_first_bit(pgdir->bits[o], MLX4_DB_PER_PAGE >> o);
>       |                                    ~~~~~~~~~~~^~~
>   'mlx4_alloc_db_from_pgdir': events 1-2
>   691 |                 i = find_first_bit(pgdir->bits[o], MLX4_DB_PER_PAGE >> o);                        |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       |                     |                         |                                                   |                     |                         (2) out of array bounds here
>       |                     (1) when the condition is evaluated to true                             In file included from ../drivers/net/ethernet/mellanox/mlx4/mlx4.h:53,
>                  from ../drivers/net/ethernet/mellanox/mlx4/alloc.c:42:
> ../include/linux/mlx4/device.h:664:33: note: while referencing 'bits'
>   664 |         unsigned long          *bits[2];
>       |                                 ^~~~
> 
> Switch the argument to unsigned int, which removes the compiler needing
> to consider negative values.
> 
> Signed-off-by: Kees Cook <kees@...nel.org>
> ---
> Cc: Tariq Toukan <tariqt@...dia.com>
> Cc: Andrew Lunn <andrew+netdev@...n.ch>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Eric Dumazet <edumazet@...gle.com>
> Cc: Jakub Kicinski <kuba@...nel.org>
> Cc: Paolo Abeni <pabeni@...hat.com>
> Cc: Yishai Hadas <yishaih@...dia.com>
> Cc: netdev@...r.kernel.org
> Cc: linux-rdma@...r.kernel.org
> ---
>  drivers/net/ethernet/mellanox/mlx4/alloc.c | 6 +++---
>  include/linux/mlx4/device.h                | 2 +-
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx4/alloc.c b/drivers/net/ethernet/mellanox/mlx4/alloc.c
> index b330020dc0d6..f2bded847e61 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/alloc.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/alloc.c
> @@ -682,9 +682,9 @@ static struct mlx4_db_pgdir *mlx4_alloc_db_pgdir(struct device *dma_device)
>  }
>  
>  static int mlx4_alloc_db_from_pgdir(struct mlx4_db_pgdir *pgdir,
> -				    struct mlx4_db *db, int order)
> +				    struct mlx4_db *db, unsigned int order)
>  {
> -	int o;
> +	unsigned int o;
>  	int i;
>  
>  	for (o = order; o <= 1; ++o) {

  ^ Knowing now that @order can only be 0 or 1 can this for loop (and
  goto) be dropped entirely?

  The code is already short and sweet so I don't feel strongly either
  way.

> @@ -712,7 +712,7 @@ static int mlx4_alloc_db_from_pgdir(struct mlx4_db_pgdir *pgdir,
>  	return 0;
>  }
>  
> -int mlx4_db_alloc(struct mlx4_dev *dev, struct mlx4_db *db, int order)
> +int mlx4_db_alloc(struct mlx4_dev *dev, struct mlx4_db *db, unsigned int order)
>  {
>  	struct mlx4_priv *priv = mlx4_priv(dev);
>  	struct mlx4_db_pgdir *pgdir;
> diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
> index 27f42f713c89..86f0f2a25a3d 100644
> --- a/include/linux/mlx4/device.h
> +++ b/include/linux/mlx4/device.h
> @@ -1135,7 +1135,7 @@ int mlx4_write_mtt(struct mlx4_dev *dev, struct mlx4_mtt *mtt,
>  int mlx4_buf_write_mtt(struct mlx4_dev *dev, struct mlx4_mtt *mtt,
>  		       struct mlx4_buf *buf);
>  
> -int mlx4_db_alloc(struct mlx4_dev *dev, struct mlx4_db *db, int order);
> +int mlx4_db_alloc(struct mlx4_dev *dev, struct mlx4_db *db, unsigned int order);
>  void mlx4_db_free(struct mlx4_dev *dev, struct mlx4_db *db);
>  
>  int mlx4_alloc_hwq_res(struct mlx4_dev *dev, struct mlx4_hwq_resources *wqres,
> -- 
> 2.34.1
> 

Justin