RE: [PATCH] net/txgbe: fix out of bound access

["Jiawen Wu" <jiawenwu@trustnetic.com>]

On Thursday, November 16, 2023 10:07 PM, Ferruh.Yigit@amd.com wrote:
> Reported by SuSe CI [1] by GCC [2], possibly false positive. Error:
> 
>  In function 'txgbe_host_interface_command',
>      inlined from 'txgbe_host_interface_command'
>              at ../drivers/net/txgbe/base/txgbe_mng.c:104:1,
>      inlined from 'txgbe_hic_reset'
>              at ../drivers/net/txgbe/base/txgbe_mng.c:345:9:
>  ../drivers/net/txgbe/base/txgbe_mng.c:145:36:
>     error: array subscript 2 is outside array bounds ofr
>            'struct txgbe_hic_reset[1]' [-Werror=array-bounds=]
>    145 |                     buffer[bi] = rd32a(hw, TXGBE_MNGMBX, bi);
>  ../drivers/net/txgbe/base/txgbe_mng.c: In function 'txgbe_hic_reset':
>  ../drivers/net/txgbe/base/txgbe_mng.c:331:32:
>     note: at offset 8 into object 'reset_cmd' of size 8
>    331 |         struct txgbe_hic_reset reset_cmd;
>        |                                ^~~~~~~~~
> 
> Access to buffer done based on command code, the case complained by
> FW_RESET_CMD has short buffer but this code path only taken with command
> 0x30, so this shouldn't be a problem.
> 
> Adding a size check before accessing to the buffer, as this is control
> plane code, additional check shouldn't hurt.
> 
> [1]
> https://build.opensuse.org/public/build/home:bluca:dpdk/openSUSE_Factory_ARM/armv7l/dpdk-20.11/_log
> 
> [2]
> gcc 13.2.1 "cc (SUSE Linux) 13.2.1 20230912
> 
> Fixes: 35c90ecccfd4 ("net/txgbe: add EEPROM functions")
> Cc: stable@dpdk.org
> 
> Reported-by: Luca Boccassi <luca.boccassi@microsoft.com>
> Signed-off-by: Ferruh Yigit <ferruh.yigit@amd.com>
> ---
> Cc: jiawenwu@trustnetic.com
> Cc: jianwang@trustnetic.com
> 
> @Luca, I am not sure if this additional check will satisfy the compiler,
> can you please verify the patch?
> 
> @Jiawen, there is a specific handling for command 0x30, from comment it
> looks like it is Read Flash command, but it looks like this command is
> not used by the driver, if this is correct can we remove the check
> completely? Removing can be simpler way to fix the compiler error.

Thanks Ferruh. This command has been removed because flash can be read
directly by the driver. The check can be simply removed.

> ---
>  drivers/net/txgbe/base/txgbe_mng.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/txgbe/base/txgbe_mng.c b/drivers/net/txgbe/base/txgbe_mng.c
> index df7145094f84..9797b1b8b5da 100644
> --- a/drivers/net/txgbe/base/txgbe_mng.c
> +++ b/drivers/net/txgbe/base/txgbe_mng.c
> @@ -147,6 +147,10 @@ txgbe_host_interface_command(struct txgbe_hw *hw, u32 *buffer,
>  	 * two byes instead of one byte
>  	 */
>  	if (resp->cmd == 0x30) {
> +		if (length < ((dword_len + 2) << 2)) {
> +			err = TXGBE_ERR_HOST_INTERFACE_COMMAND;
> +			goto rel_out;
> +		}
>  		for (; bi < dword_len + 2; bi++)
>  			buffer[bi] = rd32a(hw, TXGBE_MNGMBX, bi);
> 
> --
> 2.34.1
>