* [PATCH] mm: debug_page_alloc: fix NULL buf in debug_guardpage_minorder_setup
@ 2026-08-06 0:45 Ye Liu
2026-08-06 1:00 ` Zi Yan
2026-08-06 1:08 ` John Hubbard
0 siblings, 2 replies; 5+ messages in thread
From: Ye Liu @ 2026-08-06 0:45 UTC (permalink / raw)
To: Andrew Morton, Vlastimil Babka
Cc: Ye Liu, Suren Baghdasaryan, Michal Hocko, Brendan Jackman,
Johannes Weiner, Zi Yan, linux-mm, linux-kernel
From: Ye Liu <liuye@kylinos.cn>
If the kernel command line includes "debug_guardpage_minorder" without
an equals sign (i.e., no value is provided), the early parameter
parser passes a NULL buf pointer to the setup function.
kstrtouint() does not perform a NULL check on its input and calls
directly into kstrtoull() which dereferences s[0] unconditionally,
leading to a NULL pointer dereference and early boot crash.
Additionally, the error path's pr_err("%s", buf) would also crash with
a NULL format argument.
Signed-off-by: Ye Liu <liuye@kylinos.cn>
---
mm/debug_page_alloc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/debug_page_alloc.c b/mm/debug_page_alloc.c
index 41e3d1f1ad96..fd2664c3c86a 100644
--- a/mm/debug_page_alloc.c
+++ b/mm/debug_page_alloc.c
@@ -22,8 +22,8 @@ static int __init debug_guardpage_minorder_setup(char *buf)
{
unsigned int res;
- if (kstrtouint(buf, 10, &res) < 0 || res > MAX_PAGE_ORDER / 2) {
- pr_err("Bad debug_guardpage_minorder value: %s\n", buf);
+ if (!buf || kstrtouint(buf, 10, &res) < 0 || res > MAX_PAGE_ORDER / 2) {
+ pr_err("Bad debug_guardpage_minorder value: %s\n", buf ?: "(missing)");
return 0;
}
_debug_guardpage_minorder = res;
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] mm: debug_page_alloc: fix NULL buf in debug_guardpage_minorder_setup
2026-08-06 0:45 [PATCH] mm: debug_page_alloc: fix NULL buf in debug_guardpage_minorder_setup Ye Liu
@ 2026-08-06 1:00 ` Zi Yan
2026-08-06 1:08 ` John Hubbard
1 sibling, 0 replies; 5+ messages in thread
From: Zi Yan @ 2026-08-06 1:00 UTC (permalink / raw)
To: Ye Liu, Andrew Morton, Vlastimil Babka
Cc: Ye Liu, Suren Baghdasaryan, Michal Hocko, Brendan Jackman,
Johannes Weiner, linux-mm, linux-kernel
On Wed Aug 5, 2026 at 8:45 PM EDT, Ye Liu wrote:
> From: Ye Liu <liuye@kylinos.cn>
>
> If the kernel command line includes "debug_guardpage_minorder" without
> an equals sign (i.e., no value is provided), the early parameter
> parser passes a NULL buf pointer to the setup function.
>
> kstrtouint() does not perform a NULL check on its input and calls
> directly into kstrtoull() which dereferences s[0] unconditionally,
> leading to a NULL pointer dereference and early boot crash.
>
> Additionally, the error path's pr_err("%s", buf) would also crash with
> a NULL format argument.
>
> Signed-off-by: Ye Liu <liuye@kylinos.cn>
> ---
> mm/debug_page_alloc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
LGTM.
Acked-by: Zi Yan <ziy@nvidia.com>
--
Best Regards,
Yan, Zi
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm: debug_page_alloc: fix NULL buf in debug_guardpage_minorder_setup
2026-08-06 0:45 [PATCH] mm: debug_page_alloc: fix NULL buf in debug_guardpage_minorder_setup Ye Liu
2026-08-06 1:00 ` Zi Yan
@ 2026-08-06 1:08 ` John Hubbard
2026-08-06 1:56 ` Ye Liu
1 sibling, 1 reply; 5+ messages in thread
From: John Hubbard @ 2026-08-06 1:08 UTC (permalink / raw)
To: Ye Liu, Andrew Morton, Vlastimil Babka
Cc: Ye Liu, Suren Baghdasaryan, Michal Hocko, Brendan Jackman,
Johannes Weiner, Zi Yan, linux-mm, linux-kernel
On 8/5/26 5:45 PM, Ye Liu wrote:
> From: Ye Liu <liuye@kylinos.cn>
>
> If the kernel command line includes "debug_guardpage_minorder" without
> an equals sign (i.e., no value is provided), the early parameter
> parser passes a NULL buf pointer to the setup function.
>
> kstrtouint() does not perform a NULL check on its input and calls
> directly into kstrtoull() which dereferences s[0] unconditionally,
> leading to a NULL pointer dereference and early boot crash.
>
> Additionally, the error path's pr_err("%s", buf) would also crash with
> a NULL format argument.
>
Maybe a "Fixes:" tag is called for?
> Signed-off-by: Ye Liu <liuye@kylinos.cn>
> ---
> mm/debug_page_alloc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/debug_page_alloc.c b/mm/debug_page_alloc.c
> index 41e3d1f1ad96..fd2664c3c86a 100644
> --- a/mm/debug_page_alloc.c
> +++ b/mm/debug_page_alloc.c
> @@ -22,8 +22,8 @@ static int __init debug_guardpage_minorder_setup(char *buf)
> {
> unsigned int res;
>
> - if (kstrtouint(buf, 10, &res) < 0 || res > MAX_PAGE_ORDER / 2) {
> - pr_err("Bad debug_guardpage_minorder value: %s\n", buf);
> + if (!buf || kstrtouint(buf, 10, &res) < 0 || res > MAX_PAGE_ORDER / 2) {
> + pr_err("Bad debug_guardpage_minorder value: %s\n", buf ?: "(missing)");
> return 0;
> }
> _debug_guardpage_minorder = res;
thanks,
--
John Hubbard
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm: debug_page_alloc: fix NULL buf in debug_guardpage_minorder_setup
2026-08-06 1:08 ` John Hubbard
@ 2026-08-06 1:56 ` Ye Liu
2026-08-06 2:36 ` John Hubbard
0 siblings, 1 reply; 5+ messages in thread
From: Ye Liu @ 2026-08-06 1:56 UTC (permalink / raw)
To: John Hubbard, Andrew Morton, Vlastimil Babka
Cc: Ye Liu, Suren Baghdasaryan, Michal Hocko, Brendan Jackman,
Johannes Weiner, Zi Yan, linux-mm, linux-kernel
在 2026/8/6 09:08, John Hubbard 写道:
> On 8/5/26 5:45 PM, Ye Liu wrote:
>> From: Ye Liu <liuye@kylinos.cn>
>>
>> If the kernel command line includes "debug_guardpage_minorder" without
>> an equals sign (i.e., no value is provided), the early parameter
>> parser passes a NULL buf pointer to the setup function.
>>
>> kstrtouint() does not perform a NULL check on its input and calls
>> directly into kstrtoull() which dereferences s[0] unconditionally,
>> leading to a NULL pointer dereference and early boot crash.
>>
>> Additionally, the error path's pr_err("%s", buf) would also crash with
>> a NULL format argument.
>>
>
> Maybe a "Fixes:" tag is called for?
>
Add the following Fixes. Thanks.
Fixes: c0a32fc5a2e4 ("mm: more intensive memory corruption debugging")
>
>> Signed-off-by: Ye Liu <liuye@kylinos.cn>
>> ---
>> mm/debug_page_alloc.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/debug_page_alloc.c b/mm/debug_page_alloc.c
>> index 41e3d1f1ad96..fd2664c3c86a 100644
>> --- a/mm/debug_page_alloc.c
>> +++ b/mm/debug_page_alloc.c
>> @@ -22,8 +22,8 @@ static int __init debug_guardpage_minorder_setup(char *buf)
>> {
>> unsigned int res;
>>
>> - if (kstrtouint(buf, 10, &res) < 0 || res > MAX_PAGE_ORDER / 2) {
>> - pr_err("Bad debug_guardpage_minorder value: %s\n", buf);
>> + if (!buf || kstrtouint(buf, 10, &res) < 0 || res > MAX_PAGE_ORDER / 2) {
>> + pr_err("Bad debug_guardpage_minorder value: %s\n", buf ?: "(missing)");
>> return 0;
>> }
>> _debug_guardpage_minorder = res;
>
> thanks,
--
Thanks,
Ye Liu
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm: debug_page_alloc: fix NULL buf in debug_guardpage_minorder_setup
2026-08-06 1:56 ` Ye Liu
@ 2026-08-06 2:36 ` John Hubbard
0 siblings, 0 replies; 5+ messages in thread
From: John Hubbard @ 2026-08-06 2:36 UTC (permalink / raw)
To: Ye Liu, Andrew Morton, Vlastimil Babka
Cc: Ye Liu, Suren Baghdasaryan, Michal Hocko, Brendan Jackman,
Johannes Weiner, Zi Yan, linux-mm, linux-kernel
On 8/5/26 6:56 PM, Ye Liu wrote:
>
>
> 在 2026/8/6 09:08, John Hubbard 写道:
>> On 8/5/26 5:45 PM, Ye Liu wrote:
>>> From: Ye Liu <liuye@kylinos.cn>
>>>
>>> If the kernel command line includes "debug_guardpage_minorder" without
>>> an equals sign (i.e., no value is provided), the early parameter
>>> parser passes a NULL buf pointer to the setup function.
>>>
>>> kstrtouint() does not perform a NULL check on its input and calls
>>> directly into kstrtoull() which dereferences s[0] unconditionally,
>>> leading to a NULL pointer dereference and early boot crash.
>>>
>>> Additionally, the error path's pr_err("%s", buf) would also crash with
>>> a NULL format argument.
>>>
>>
>> Maybe a "Fixes:" tag is called for?
>>
>
> Add the following Fixes. Thanks.
>
> Fixes: c0a32fc5a2e4 ("mm: more intensive memory corruption debugging")
>
Looks good,
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
thanks,
--
John Hubbard
>>
>>> Signed-off-by: Ye Liu <liuye@kylinos.cn>
>>> ---
>>> mm/debug_page_alloc.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/mm/debug_page_alloc.c b/mm/debug_page_alloc.c
>>> index 41e3d1f1ad96..fd2664c3c86a 100644
>>> --- a/mm/debug_page_alloc.c
>>> +++ b/mm/debug_page_alloc.c
>>> @@ -22,8 +22,8 @@ static int __init debug_guardpage_minorder_setup(char *buf)
>>> {
>>> unsigned int res;
>>>
>>> - if (kstrtouint(buf, 10, &res) < 0 || res > MAX_PAGE_ORDER / 2) {
>>> - pr_err("Bad debug_guardpage_minorder value: %s\n", buf);
>>> + if (!buf || kstrtouint(buf, 10, &res) < 0 || res > MAX_PAGE_ORDER / 2) {
>>> + pr_err("Bad debug_guardpage_minorder value: %s\n", buf ?: "(missing)");
>>> return 0;
>>> }
>>> _debug_guardpage_minorder = res;
>>
>> thanks,
>
^ permalink raw reply [flat|nested] 5+ messages in thread
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2026-08-06 0:45 [PATCH] mm: debug_page_alloc: fix NULL buf in debug_guardpage_minorder_setup Ye Liu
2026-08-06 1:00 ` Zi Yan
2026-08-06 1:08 ` John Hubbard
2026-08-06 1:56 ` Ye Liu
2026-08-06 2:36 ` John Hubbard
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