[PATCH RESEND] x86/boot: Replace simple_strtoull in parse_gb_huge_pages

[PATCH RESEND] x86/boot: Replace simple_strtoull in parse_gb_huge_pages

[Thorsten Blum]

Replace simple_strtoull() with the recommended boot_kstrtoul() for
parsing the 'hugepages=' boot parameter. Unlike simple_strtoull(), which
returns an unsigned long long, boot_kstrtoul() converts the string
directly to an unsigned long and avoids implicit casting.

Check the return value of boot_kstrtoul() and warn about invalid values.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 arch/x86/boot/compressed/kaslr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 3b0948ad449f..e6c44a0d3640 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -219,7 +219,8 @@ static void parse_gb_huge_pages(char *param, char *val)
 
 	if (!strcmp(param, "hugepages") && gbpage_sz) {
 		p = val;
-		max_gb_huge_pages = simple_strtoull(p, &p, 0);
+		if (boot_kstrtoul(p, 0, &max_gb_huge_pages))
+			warn("Failed to parse boot parameter hugepages\n");
 		return;
 	}
 }
-- 
Thorsten Blum <thorsten.blum@linux.dev>
GPG: 1D60 735E 8AEF 3BE4 73B6  9D84 7336 78FD 8DFE EAD4

Re: [PATCH RESEND] x86/boot: Replace simple_strtoull in parse_gb_huge_pages

[Borislav Petkov]

On Mon, Feb 02, 2026 at 06:32:20PM +0100, Thorsten Blum wrote:
> Replace simple_strtoull() with the recommended boot_kstrtoul() for
> parsing the 'hugepages=' boot parameter. Unlike simple_strtoull(), which
> returns an unsigned long long, boot_kstrtoul() converts the string
> directly to an unsigned long and avoids implicit casting.

"The respective kstrtol(), kstrtoll(), kstrtoul(), and kstrtoull() functions
tend to be the correct replacements, though note that those require the string
to be NUL or newline terminated."

Where are we making sure of that?

> Check the return value of boot_kstrtoul() and warn about invalid values.
> 
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> ---
>  arch/x86/boot/compressed/kaslr.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> index 3b0948ad449f..e6c44a0d3640 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -219,7 +219,8 @@ static void parse_gb_huge_pages(char *param, char *val)
>  
>  	if (!strcmp(param, "hugepages") && gbpage_sz) {
>  		p = val;
> -		max_gb_huge_pages = simple_strtoull(p, &p, 0);
> +		if (boot_kstrtoul(p, 0, &max_gb_huge_pages))
> +			warn("Failed to parse boot parameter hugepages\n");

Make that

	warn("Failed to parse hugepages= boot parameter\n");

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [PATCH RESEND] x86/boot: Replace simple_strtoull in parse_gb_huge_pages

[Thorsten Blum]

On 1. Mar 2026, at 11:44, Borislav Petkov wrote:
> On Mon, Feb 02, 2026 at 06:32:20PM +0100, Thorsten Blum wrote:
>> Replace simple_strtoull() with the recommended boot_kstrtoul() for
>> parsing the 'hugepages=' boot parameter. Unlike simple_strtoull(), which
>> returns an unsigned long long, boot_kstrtoul() converts the string
>> directly to an unsigned long and avoids implicit casting.
> 
> "The respective kstrtol(), kstrtoll(), kstrtoul(), and kstrtoull() functions
> tend to be the correct replacements, though note that those require the string
> to be NUL or newline terminated."
> 
> Where are we making sure of that?

next_arg() provides NUL-terminated substrings, but 'val' could be NULL
when '=' is missing in the boot parameter, but that would also break
memparse() and simple_strtoull().

Should I fix this for both 'hugepagesz' and 'hugepages' in this patch?
Something like this:

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 3b0948ad449f..b98b574dd937 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -202,9 +202,15 @@ static unsigned long max_gb_huge_pages;
 static void parse_gb_huge_pages(char *param, char *val)
 {
 	static bool gbpage_sz;
-	char *p;
 
 	if (!strcmp(param, "hugepagesz")) {
+		char *p;
+
+		if (!val) {
+			warn("Missing value in hugepagesz= boot parameter\n");
+			return;
+		}
+
 		p = val;
 		if (memparse(p, &p) != PUD_SIZE) {
 			gbpage_sz = false;
@@ -218,8 +224,13 @@ static void parse_gb_huge_pages(char *param, char *val)
 	}
 
 	if (!strcmp(param, "hugepages") && gbpage_sz) {
-		p = val;
-		max_gb_huge_pages = simple_strtoull(p, &p, 0);
+		if (!val) {
+			warn("Missing value in hugepages= boot parameter\n");
+			return;
+		}
+
+		if (boot_kstrtoul(val, 0, &max_gb_huge_pages))
+			warn("Failed to parse hugepages= boot parameter\n");
 		return;
 	}
 }

Re: [PATCH RESEND] x86/boot: Replace simple_strtoull in parse_gb_huge_pages

[David Laight]

On Sun, 1 Mar 2026 11:44:54 +0100
Borislav Petkov <bp@alien8.de> wrote:

> On Mon, Feb 02, 2026 at 06:32:20PM +0100, Thorsten Blum wrote:
> > Replace simple_strtoull() with the recommended boot_kstrtoul() for
> > parsing the 'hugepages=' boot parameter. Unlike simple_strtoull(), which
> > returns an unsigned long long, boot_kstrtoul() converts the string
> > directly to an unsigned long and avoids implicit casting.  
> 
> "The respective kstrtol(), kstrtoll(), kstrtoul(), and kstrtoull() functions
> tend to be the correct replacements, though note that those require the string
> to be NUL or newline terminated."
> 
> Where are we making sure of that?
> 
> > Check the return value of boot_kstrtoul() and warn about invalid values.
> > 
> > Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> > ---
> >  arch/x86/boot/compressed/kaslr.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> > index 3b0948ad449f..e6c44a0d3640 100644
> > --- a/arch/x86/boot/compressed/kaslr.c
> > +++ b/arch/x86/boot/compressed/kaslr.c
> > @@ -219,7 +219,8 @@ static void parse_gb_huge_pages(char *param, char *val)
> >  
> >  	if (!strcmp(param, "hugepages") && gbpage_sz) {
> >  		p = val;
> > -		max_gb_huge_pages = simple_strtoull(p, &p, 0);
> > +		if (boot_kstrtoul(p, 0, &max_gb_huge_pages))
> > +			warn("Failed to parse boot parameter hugepages\n");  
> 
> Make that
> 
> 	warn("Failed to parse hugepages= boot parameter\n");
> 

I'd suggest including the 'val' that failed to parse.

	David

Re: [PATCH RESEND] x86/boot: Replace simple_strtoull in parse_gb_huge_pages

[Thorsten Blum]

On 1. Mar 2026, at 19:30, David Laight wrote:
> On Sun, 1 Mar 2026 11:44:54 +0100 Borislav Petkov wrote:
>> On Mon, Feb 02, 2026 at 06:32:20PM +0100, Thorsten Blum wrote:
>>> Replace simple_strtoull() with the recommended boot_kstrtoul() for
>>> parsing the 'hugepages=' boot parameter. Unlike simple_strtoull(), which
>>> returns an unsigned long long, boot_kstrtoul() converts the string
>>> directly to an unsigned long and avoids implicit casting.  
>> 
>> "The respective kstrtol(), kstrtoll(), kstrtoul(), and kstrtoull() functions
>> tend to be the correct replacements, though note that those require the string
>> to be NUL or newline terminated."
>> 
>> Where are we making sure of that?
>> 
>>> Check the return value of boot_kstrtoul() and warn about invalid values.
>>> 
>>> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
>>> ---
>>> arch/x86/boot/compressed/kaslr.c | 3 ++-
>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>> [...]
>> 
>> Make that
>> 
>> warn("Failed to parse hugepages= boot parameter\n");
> 
> I'd suggest including the 'val' that failed to parse.

warn() isn't variadic and cannot print format arguments. We could add
another helper (e.g., warn_param()) or use error_putstr() manually, but
I'm not sure it's worth it for this case. Any other thoughts on this?

Thanks,
Thorsten