[PATCH v2] arm: mach-snapdragon: increase compat buffer size and warn on root compatible string truncation

[Casey Connolly]

Hi Vivek,

On 10/06/2026 15:54, Vivek Ray wrote:
> The configure_env() function copies root compatible strings into a
> 32-byte buffer prior to parsing. If a compatible string exceeds this
> limit, strlcpy() silently truncates it, producing a malformed fdtfile
> path and a silent boot failure with no indication of the root cause.
> 
> Bump buf[] to 128 bytes and dt_path[] to 256 bytes to accommodate longer
> compatible strings. Also, add explicit truncation checks after both
> strlcpy() calls and emit a log_warning() with the offending compatible
> string to make such failures easier to diagnose.
> 
> Signed-off-by: Vivek Ray <vk092kumar at gmail.com>

Thanks for the quick respin!

Reviewed-by: Casey Connolly <casey.connolly at linaro.org>

> 
> ---
> 
> Changes in V2:
> - Bump buf[] from 32 to 128 bytes and dt_path[] from 64 to 256 (Casey Connolly)
> - Fix line size check, use > not >= (Casey Connolly)
> 
> ---
>  arch/arm/mach-snapdragon/board.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/mach-snapdragon/board.c b/arch/arm/mach-snapdragon/board.c
> index 829a0109ac7..d9390d9b5d3 100644
> --- a/arch/arm/mach-snapdragon/board.c
> +++ b/arch/arm/mach-snapdragon/board.c
> @@ -390,13 +390,14 @@ static void configure_env(void)
>  {
>  	const char *first_compat, *last_compat;
>  	char *tmp;
> -	char buf[32] = { 0 };
> +	char buf[128] = { 0 };
> +	int len = 0;
>  	/*
>  	 * Most DTB filenames follow the scheme: qcom/<soc>-[vendor]-<board>.dtb
>  	 * The vendor is skipped when it's a Qualcomm reference board, or the
>  	 * db845c.
>  	 */
> -	char dt_path[64] = { 0 };
> +	char dt_path[256] = { 0 };
>  	int compat_count, ret;
>  	ofnode root;
>  
> @@ -417,7 +418,11 @@ static void configure_env(void)
>  		return;
>  	}
>  
> -	strlcpy(buf, first_compat, sizeof(buf) - 1);
> +	/* A safety check to avoid silent failure due to name truncation */
> +	len = strlcpy(buf, first_compat, sizeof(buf) - 1);
> +	if (len > sizeof(buf) - 1)
> +		log_warning("compatible '%s' got truncated, fdtfile name too long\n",
> +			    first_compat);
>  	tmp = buf;
>  
>  	/* The Qualcomm reference boards (RBx, HDK, etc)  */
> @@ -468,7 +473,12 @@ static void configure_env(void)
>  
>  		/* Copy the last compat (e.g. "qcom,sdm845") into buf */
>  		memset(buf, 0, sizeof(buf));
> -		strlcpy(buf, last_compat, sizeof(buf) - 1);
> +
> +		/* check for name truncation */
> +		len = strlcpy(buf, last_compat, sizeof(buf) - 1);
> +		if (len > sizeof(buf) - 1)
> +			log_warning("compatible '%s' got truncated, fdtfile name too long\n",
> +				    last_compat);
>  		tmp = buf;
>  
>  		/* strsep() is destructive, it replaces the comma with a \0 */

-- 
// Casey (she/her)