[PATCH] EDAC: fix a limit calculation in calculate_dimm_size()

[PATCH] EDAC: fix a limit calculation in calculate_dimm_size()

[Dan Carpenter]

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@linaro.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

RE: [PATCH] EDAC: fix a limit calculation in calculate_dimm_size()

[Zhuo, Qiuxu]

Hi Dan,

> From: Dan Carpenter <dan.carpenter@linaro.org>
> Sent: Friday, December 5, 2025 7:10 PM
> To: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: Borislav Petkov <bp@alien8.de>; Luck, Tony <tony.luck@intel.com>;
> Aristeu Rozanski <arozansk@redhat.com>; linux-edac@vger.kernel.org; linux-
> kernel@vger.kernel.org; kernel-janitors@vger.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@linaro.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@intel.com>

Re: [PATCH] EDAC: fix a limit calculation in calculate_dimm_size()

[Dan Carpenter]

Thanks for the review.  All good points.  I have resent the patch.

regards,
dan carpenter

RE: [PATCH] EDAC: fix a limit calculation in calculate_dimm_size()

[Zhuo, Qiuxu]

> From: Dan Carpenter <dan.carpenter@linaro.org>
> Sent: Tuesday, December 9, 2025 10:38 PM
> To: Zhuo, Qiuxu <qiuxu.zhuo@intel.com>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>; Borislav Petkov
> <bp@alien8.de>; Luck, Tony <tony.luck@intel.com>; Aristeu Rozanski
> <arozansk@redhat.com>; linux-edac@vger.kernel.org; linux-
> kernel@vger.kernel.org; kernel-janitors@vger.kernel.org
> Subject: Re: [PATCH] EDAC: fix a limit calculation in calculate_dimm_size()
> 
> Thanks for the review.  All good points.  I have resent the patch.
> 

Thanks for your update.

-Qiuxu