linux-kernel - RE: [PATCH] EDAC: fix a limit calculation in calculate_dimm

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Message-ID: <CY8PR11MB713404B614F5D046E94DE2A289A7A@CY8PR11MB7134.namprd11.prod.outlook.com>
Date: Fri, 5 Dec 2025 15:36:03 +0000
From: "Zhuo, Qiuxu" <qiuxu.zhuo@...el.com>
To: Dan Carpenter <dan.carpenter@...aro.org>, Mauro Carvalho Chehab
	<mchehab@...nel.org>
CC: Borislav Petkov <bp@...en8.de>, "Luck, Tony" <tony.luck@...el.com>,
	Aristeu Rozanski <arozansk@...hat.com>, "linux-edac@...r.kernel.org"
	<linux-edac@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "kernel-janitors@...r.kernel.org"
	<kernel-janitors@...r.kernel.org>
Subject: RE: [PATCH] EDAC: fix a limit calculation in calculate_dimm_size()

Hi Dan,

> From: Dan Carpenter <dan.carpenter@...aro.org>
> Sent: Friday, December 5, 2025 7:10 PM
> To: Mauro Carvalho Chehab <mchehab@...nel.org>
> Cc: Borislav Petkov <bp@...en8.de>; Luck, Tony <tony.luck@...el.com>;
> Aristeu Rozanski <arozansk@...hat.com>; linux-edac@...r.kernel.org; linux-
> kernel@...r.kernel.org; kernel-janitors@...r.kernel.org
> Subject: [PATCH] EDAC: fix a limit calculation in calculate_dimm_size()

Please use the subject style as in most other EDAC files:

  EDAC/i5400: Fix a limit calculation in calculate_dimm_size()

> 
> The snprintf() can't really overflow because we're writing a max of 42 bytes to
> a PAGE_SIZE buffer.  But my static checker complains because the limit
> calculation doesn't take the first 11 bytes into consideration.
> Fix this for the sake of correctness even though it doesn't affect runtime.
> 
> Fixes: 68d086f89b80 ("i5400_edac: improve debug messages to better
> represent the filled memory")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> ---
>  drivers/edac/i5400_edac.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/edac/i5400_edac.c b/drivers/edac/i5400_edac.c index
> b5cf25905b05..81c93ba957a0 100644
> --- a/drivers/edac/i5400_edac.c
> +++ b/drivers/edac/i5400_edac.c
> @@ -1033,6 +1033,7 @@ static void calculate_dimm_size(struct i5400_pvt
> *pvt)
> 
>  	n = snprintf(p, space, "           ");
>  	p += n;
> +	space -= n;
>  	for (branch = 0; branch < MAX_BRANCHES; branch++) {
>  		n = snprintf(p, space, "       branch %d       | ", branch);
>  		p += n;
> --
> 2.51.0
> 

At line 1029 in the original i5400_edac.c file, there is an incorrect extra "space -= n;" code line.
Please also remove it.

   https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/edac/i5400_edac.c#n1029

If with the above extra fix, your subject may need to update as follows:

  EDAC/i5400: Fix limit calculations in calculate_dimm_size()

Other than that,

   Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@...el.com>