Add some warnings for using ethtool_sprintf() where a simple
ethtool_puts() would suffice.

The two cases are:

1) Use ethtool_sprintf() with just two arguments:
|       ethtool_sprintf(&data, driver[i].name);
or
2) Use ethtool_sprintf() with a standalone "%s" fmt string:
|       ethtool_sprintf(&data, "%s", driver[i].name);

The former may cause -Wformat-security warnings while the latter is just
not preferred. Both are safely in the category of warnings, not errors.

Signed-off-by: Justin Stitt <justinstitt@google.com>
---
 scripts/checkpatch.pl | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 25fdb7fda112..6924731110d8 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -7011,6 +7011,25 @@ sub process {
 			     "Prefer strscpy, strscpy_pad, or __nonstring over strncpy - see: https://github.com/KSPP/linux/issues/90\n" . $herecurr);
 		}
 
+# ethtool_sprintf uses that should likely be ethtool_puts
+		if ($line =~ /\bethtool_sprintf\s*\(\s*$FuncArg\s*,\s*$FuncArg\s*\)/) {
+			if (WARN("PREFER_ETHTOOL_PUTS",
+				 "Prefer ethtool_puts over ethtool_sprintf with only two arguments\n" . $herecurr) &&
+			    $fix) {
+				$fixed[$fixlinenr] =~ s/\bethtool_sprintf\s*\(\s*($FuncArg)\s*,\s*($FuncArg)/ethtool_puts($1, $7)/;
+			}
+		}
+
+		# use $rawline because $line loses %s via sanitization and thus we can't match against it.
+		if ($rawline =~ /\bethtool_sprintf\s*\(\s*$FuncArg\s*,\s*\"\%s\"\s*,\s*$FuncArg\s*\)/) {
+			if (WARN("PREFER_ETHTOOL_PUTS",
+				 "Prefer ethtool_puts over ethtool_sprintf with standalone \"%s\" specifier\n" . $herecurr) &&
+			    $fix) {
+				$fixed[$fixlinenr] =~ s/\bethtool_sprintf\s*\(\s*($FuncArg)\s*,\s*"\%s"\s*,\s*($FuncArg)/ethtool_puts($1, $7)/;
+			}
+		}
+
+
 # typecasts on min/max could be min_t/max_t
 		if ($perl_version_ok &&
 		    defined $stat &&

-- 
2.43.0.rc2.451.g8631bc7472-goog

On 12/7/23 00:16, justinstitt@google.com wrote:
> Add some warnings for using ethtool_sprintf() where a simple
> ethtool_puts() would suffice.
> 
> The two cases are:
> 
> 1) Use ethtool_sprintf() with just two arguments:
> |       ethtool_sprintf(&data, driver[i].name);
> or
> 2) Use ethtool_sprintf() with a standalone "%s" fmt string:
> |       ethtool_sprintf(&data, "%s", driver[i].name);
> 
> The former may cause -Wformat-security warnings while the latter is just
> not preferred. Both are safely in the category of warnings, not errors.
> 
> Signed-off-by: Justin Stitt <justinstitt@google.com>
> ---
>   scripts/checkpatch.pl | 19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)
> 

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>

> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 25fdb7fda112..6924731110d8 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -7011,6 +7011,25 @@ sub process {
>   			     "Prefer strscpy, strscpy_pad, or __nonstring over strncpy - see: https://github.com/KSPP/linux/issues/90\n" . $herecurr);
>   		}
>   
> +# ethtool_sprintf uses that should likely be ethtool_puts
> +		if ($line =~ /\bethtool_sprintf\s*\(\s*$FuncArg\s*,\s*$FuncArg\s*\)/) {
> +			if (WARN("PREFER_ETHTOOL_PUTS",
> +				 "Prefer ethtool_puts over ethtool_sprintf with only two arguments\n" . $herecurr) &&
> +			    $fix) {
> +				$fixed[$fixlinenr] =~ s/\bethtool_sprintf\s*\(\s*($FuncArg)\s*,\s*($FuncArg)/ethtool_puts($1, $7)/;
> +			}
> +		}
> +
> +		# use $rawline because $line loses %s via sanitization and thus we can't match against it.
> +		if ($rawline =~ /\bethtool_sprintf\s*\(\s*$FuncArg\s*,\s*\"\%s\"\s*,\s*$FuncArg\s*\)/) {
> +			if (WARN("PREFER_ETHTOOL_PUTS",
> +				 "Prefer ethtool_puts over ethtool_sprintf with standalone \"%s\" specifier\n" . $herecurr) &&
> +			    $fix) {
> +				$fixed[$fixlinenr] =~ s/\bethtool_sprintf\s*\(\s*($FuncArg)\s*,\s*"\%s"\s*,\s*($FuncArg)/ethtool_puts($1, $7)/;

(not related to the patch)
without deeper digging it was completely unclear why it is $7 for the
"second" capture group, turns out that FuncArg contains parens and other
vars with parens :~

> +			}
> +		}
> +
> +
>   # typecasts on min/max could be min_t/max_t
>   		if ($perl_version_ok &&
>   		    defined $stat &&
>