[PATCH 0/2] Doc, scripts: facilitate phaseout of strlcat

[PATCH 0/2] Doc, scripts: facilitate phaseout of strlcat

[Manuel Ebner]

The goal of this series is to facilitate the transition from strlcat to better
alternatives.

[PATCH 1/2] [PATCH 1/2] Doc: deprecated.rst: add strlcat()

[Manuel Ebner]

add strlcat and alternatives
---
 Documentation/process/deprecated.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
index fed56864d036..b8a65c19796c 100644
--- a/Documentation/process/deprecated.rst
+++ b/Documentation/process/deprecated.rst
@@ -162,6 +162,12 @@ if a source string is not NUL-terminated. The safe replacement is strscpy(),
 though care must be given to any cases where the return value of strlcpy()
 is used, since strscpy() will return negative errno values when it truncates.
 
+strlcat()
+---------
+strlcat() must re-scan the destination string from the beginning on each
+call (O(n^2) behavior). Alternatives are seq_buf_puts(), seq_buf_printf(),
+snprintf() and scnprintf()
+
 %p format specifier
 -------------------
 Traditionally, using "%p" in format strings would lead to regular address
-- 
2.54.0

[PATCH 1/2] Doc: deprecated.rst: add strlcat()

[Manuel Ebner]

add strlcat and alternatives

Signed-off-by: Manuel Ebner <manuelebner@mailbox.org>
---
 Documentation/process/deprecated.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
index fed56864d036..b8a65c19796c 100644
--- a/Documentation/process/deprecated.rst
+++ b/Documentation/process/deprecated.rst
@@ -162,6 +162,12 @@ if a source string is not NUL-terminated. The safe replacement is strscpy(),
 though care must be given to any cases where the return value of strlcpy()
 is used, since strscpy() will return negative errno values when it truncates.
 
+strlcat()
+---------
+strlcat() must re-scan the destination string from the beginning on each
+call (O(n^2) behavior). Alternatives are seq_buf_puts(), seq_buf_printf(),
+snprintf() and scnprintf()
+
 %p format specifier
 -------------------
 Traditionally, using "%p" in format strings would lead to regular address
-- 
2.54.0

Re: [PATCH 1/2] Doc: deprecated.rst: add strlcat()

[Randy Dunlap]

On 5/10/26 9:54 AM, Manuel Ebner wrote:
> add strlcat and alternatives
> 
> Signed-off-by: Manuel Ebner <manuelebner@mailbox.org>
> ---
>  Documentation/process/deprecated.rst | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
> index fed56864d036..b8a65c19796c 100644
> --- a/Documentation/process/deprecated.rst
> +++ b/Documentation/process/deprecated.rst
> @@ -162,6 +162,12 @@ if a source string is not NUL-terminated. The safe replacement is strscpy(),
>  though care must be given to any cases where the return value of strlcpy()
>  is used, since strscpy() will return negative errno values when it truncates.
>  
> +strlcat()
> +---------
> +strlcat() must re-scan the destination string from the beginning on each
> +call (O(n^2) behavior). Alternatives are seq_buf_puts(), seq_buf_printf(),
> +snprintf() and scnprintf()

Add an ending period.

> +
>  %p format specifier
>  -------------------
>  Traditionally, using "%p" in format strings would lead to regular address

-- 
~Randy

[PATCH 2/2] scripts: checkpatch.pl: add warning for strlcat()

[Manuel Ebner]

add a warning for strlcat()

Signed-off-by: Manuel Ebner <manuelebner@mailbox.org>
---
 scripts/checkpatch.pl | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 0492d6afc9a1..ca1a8e67d529 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -7085,6 +7085,12 @@ sub process {
 			     "Prefer strscpy over strlcpy - see: https://github.com/KSPP/linux/issues/89\n" . $herecurr);
 		}
 
+# strlcat uses that should likely be
+		if ($line =~ /\bstrlcat\s*\(/ && !is_userspace($realfile)) {
+			WARN("STRLCAT",
+			     "Prefer seq_buf_printf() over strlcat - see: https://github.com/KSPP/linux/issues/370\n" . $herecurr);
+		}
+
 # strncpy uses that should likely be strscpy or strscpy_pad
 		if ($line =~ /\bstrncpy\s*\(/ && !is_userspace($realfile)) {
 			WARN("STRNCPY",
-- 
2.54.0

Re: [PATCH 2/2] scripts: checkpatch.pl: add warning for strlcat()

[Randy Dunlap]

On 5/10/26 9:56 AM, Manuel Ebner wrote:
> add a warning for strlcat()
> 
> Signed-off-by: Manuel Ebner <manuelebner@mailbox.org>
> ---
>  scripts/checkpatch.pl | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 0492d6afc9a1..ca1a8e67d529 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -7085,6 +7085,12 @@ sub process {
>  			     "Prefer strscpy over strlcpy - see: https://github.com/KSPP/linux/issues/89\n" . $herecurr);
>  		}
>  
> +# strlcat uses that should likely be

should likely be what?

> +		if ($line =~ /\bstrlcat\s*\(/ && !is_userspace($realfile)) {
> +			WARN("STRLCAT",
> +			     "Prefer seq_buf_printf() over strlcat - see: https://github.com/KSPP/linux/issues/370\n" . $herecurr);
> +		}
> +
>  # strncpy uses that should likely be strscpy or strscpy_pad
>  		if ($line =~ /\bstrncpy\s*\(/ && !is_userspace($realfile)) {
>  			WARN("STRNCPY",

-- 
~Randy