[PATCH v5 2/4] edac: Add L3 EDAC support to the APM X-Gene SoC EDAC driver

[bp@alien8.de (Borislav Petkov)]

On Wed, Sep 23, 2015 at 05:40:59PM -0700, Loc Ho wrote:
> Add EDAC support for the L3 component.
> 
> Signed-off-by: Loc Ho <lho@apm.com>
> ---
>  drivers/edac/xgene_edac.c |  669 ++++++++++++++++++++++++++++++++-------------
>  1 files changed, 474 insertions(+), 195 deletions(-)

...

> @@ -878,25 +869,16 @@ static const struct file_operations xgene_edac_pmd_debug_inject_fops[] = {
>  	{ }
>  };
> 
> -static void xgene_edac_pmd_create_debugfs_nodes(
> -	struct edac_device_ctl_info *edac_dev)
> +static void
> +xgene_edac_pmd_create_debugfs_nodes(struct edac_device_ctl_info *edac_dev)
>  {
>  	struct xgene_edac_pmd_ctx *ctx = edac_dev->pvt_info;
>  	struct dentry *dbgfs_dir;
> -	char name[30];
> +	char name[10];

So somehow we don't seem to understand each other. This char name[10] on
the stack thing has a bunch of problems:

1. It is on the stack so it contains random garbage.

> 
> -	if (!IS_ENABLED(CONFIG_EDAC_DEBUG))
> +	if (!IS_ENABLED(CONFIG_EDAC_DEBUG) || !ctx->edac->dfs)
>  		return;
> 
> -	/*
> -	 * Todo: Switch to common EDAC debug file system for edac device
> -	 *       when available.
> -	 */
> -	if (!ctx->edac->dfs) {
> -		ctx->edac->dfs = edac_debugfs_create_dir(edac_dev->dev->kobj.name);
> -		if (!ctx->edac->dfs)
> -			return;
> -	}
>  	sprintf(name, "PMD%d", ctx->pmd);

2. You're sprintf-ing into it without checking its length. This can
possibly write past the end if %d is big enough. I know, I know, %d
is only small numbers but that assurance not good enough. You need
snprintf() and check the ctx->pmd width for sane numbers only anyway.

And debugfs goes and does strlen() on it which could lead to all kinds
of funky stuff later.

Please fix that in all its occurrences in this patchset.

-- 
Regards/Gruss,
    Boris.

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