RE: [Intel-wired-lan] MMIO write access to an invalid page in i40e_clear_hw()

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@xxxxxxxxxx> On Behalf Of
> Kyungwook Boo
> Sent: Monday, March 3, 2025 11:20 AM
> To: Nguyen, Anthony L <anthony.l.nguyen@xxxxxxxxx>; Kitszel, Przemyslaw
> <przemyslaw.kitszel@xxxxxxxxx>
> Cc: intel-wired-lan@xxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: [Intel-wired-lan] MMIO write access to an invalid page in
> i40e_clear_hw()
> 
Please start commit title with 'fix' to explicitly tell what your patch do i.e. :
Ice: fix MMIO write access to an invalid page in  i40e_clear_hw


> Hello,
> 
> It seems that there are invalid page MMIO write access in i40e_clear_hw() due
> to an integer underflow from num_pf_int(also num_vf_int seems possible).
> 
> The following is a sample code in i40e_clear_hw():
> 
> val = rd32(hw, I40E_GLPCI_CNF2); // (1)
> num_pf_int = FIELD_GET(I40E_GLPCI_CNF2_MSI_X_PF_N_MASK, val); // (2)
> num_vf_int = FIELD_GET(I40E_GLPCI_CNF2_MSI_X_VF_N_MASK, val); ...
> for (i = 0; i < num_pf_int - 2; i++)      // (3)
> 	wr32(hw, I40E_PFINT_DYN_CTLN(i), val);  // (4) ...
> for (i = 0; i < num_pf_int - 2; i++)			// (5)
> 	wr32(hw, I40E_PFINT_LNKLSTN(i), val);
> ...
> for (i = 0; i < num_vf_int - 2; i++)			// (6)
> 	wr32(hw, I40E_VPINT_LNKLSTN(i), val);
> 
> An example scenario for num_pf_int:
> (1) val = 0 (if MMIO read value was 0)
> (2) num_pf_int = 0 (also zero after bit field extraction from val)
> (3) An integer underflow occurs (num_pf_int - 2 == 0xfffffffe)
> (4) Out-of-bounds MMIO write access if access address exceeds the expected
> range.
> 
> From above example scenario, the maximum access offset value can be
> around
> 0x4000347f8(=172G) which seems like this underflow is not intended(also
> there are masking operations like (2) for num_pf_int), so I report this issue.
> 
> I think similar issue also could happen at (5) and (6).
> 
> The following is the patch method I propose:
> 
Please add Fixes: tag  https://www.kernel.org/doc/html/latest/process/submitting-patches.html


> diff --git a/drivers/net/ethernet/intel/i40e/i40e_common.c
> b/drivers/net/ethernet/intel/i40e/i40e_common.c
> index 370b4bddee44..97ef79be39b3 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_common.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_common.c
> @@ -848,19 +848,25 @@ void i40e_clear_hw(struct i40e_hw *hw)
>  	/* stop all the interrupts */
>  	wr32(hw, I40E_PFINT_ICR0_ENA, 0);
>  	val = 0x3 << I40E_PFINT_DYN_CTLN_ITR_INDX_SHIFT;
> -	for (i = 0; i < num_pf_int - 2; i++)
> -		wr32(hw, I40E_PFINT_DYN_CTLN(i), val);
> +	if (num_pf_int > 1) {
> +		for (i = 0; i < num_pf_int - 2; i++)
> +			wr32(hw, I40E_PFINT_DYN_CTLN(i), val);
> +	}
> 
>  	/* Set the FIRSTQ_INDX field to 0x7FF in PFINT_LNKLSTx */
>  	val = eol << I40E_PFINT_LNKLST0_FIRSTQ_INDX_SHIFT;
>  	wr32(hw, I40E_PFINT_LNKLST0, val);
> -	for (i = 0; i < num_pf_int - 2; i++)
> -		wr32(hw, I40E_PFINT_LNKLSTN(i), val);
> +	if (num_pf_int > 1) {
> +		for (i = 0; i < num_pf_int - 2; i++)
> +			wr32(hw, I40E_PFINT_LNKLSTN(i), val);
> +	}
Can you consider moving this if upper and use it once instead of duplicating the code?
I think it can help to maintain the code. What do you think?

>  	val = eol << I40E_VPINT_LNKLST0_FIRSTQ_INDX_SHIFT;
>  	for (i = 0; i < num_vfs; i++)
>  		wr32(hw, I40E_VPINT_LNKLST0(i), val);
> -	for (i = 0; i < num_vf_int - 2; i++)
> -		wr32(hw, I40E_VPINT_LNKLSTN(i), val);
> +	if (num_vf_int > 1) {
> +		for (i = 0; i < num_vf_int - 2; i++)
> +			wr32(hw, I40E_VPINT_LNKLSTN(i), val);
> +	}
> 
>  	/* warn the HW of the coming Tx disables */
>  	for (i = 0; i < num_queues; i++) {
> 
> 
> Could you check this?
> 
> Best regards,
> Kyungwook Boo