From: Chao Yu <[email protected]>
As Christophe JAILLET suggested:
In create_unique_id(),
"looks that ID_STR_LENGTH could even be reduced to 32 or 16.
The 2nd BUG_ON at the end of the function could certainly be just
removed as well or remplaced by a:
if (p > name + ID_STR_LENGTH - 1) {
kfree(name);
return -E<something>;
}
"
According to above suggestion, let's do below cleanups:
1. reduce ID_STR_LENGTH to 32, as the buffer size should be enough;
2. remove BUG_ON() and return error if check condition is true.
Link: https://lore.kernel.org/linux-mm/[email protected]/
Suggested-by: Christophe JAILLET <[email protected]>
Fixes: 81819f0fc828 ("SLUB core")
Signed-off-by: Chao Yu <[email protected]>
---
mm/slub.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 5ba6db62a5ab..a045c1ca8772 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5883,7 +5883,7 @@ static inline struct kset *cache_kset(struct kmem_cache *s)
return slab_kset;
}
-#define ID_STR_LENGTH 64
+#define ID_STR_LENGTH 32
/* Create a unique string id for a slab cache:
*
@@ -5919,7 +5919,10 @@ static char *create_unique_id(struct kmem_cache *s)
*p++ = '-';
p += sprintf(p, "%07u", s->size);
- BUG_ON(p > name + ID_STR_LENGTH - 1);
+ if (p > name + ID_STR_LENGTH - 1) {
+ kfree(name);
+ return ERR_PTR(-EINVAL);
+ }
return name;
}
--
2.25.1
On Sun, Sep 18, 2022 at 05:21:46PM +0800, Chao Yu wrote:
> From: Chao Yu <[email protected]>
>
> As Christophe JAILLET suggested:
>
> In create_unique_id(),
>
> "looks that ID_STR_LENGTH could even be reduced to 32 or 16.
>
> The 2nd BUG_ON at the end of the function could certainly be just
> removed as well or remplaced by a:
> if (p > name + ID_STR_LENGTH - 1) {
> kfree(name);
> return -E<something>;
> }
> "
>
> According to above suggestion, let's do below cleanups:
> 1. reduce ID_STR_LENGTH to 32, as the buffer size should be enough;
> 2. remove BUG_ON() and return error if check condition is true.
>
> Link: https://lore.kernel.org/linux-mm/[email protected]/
> Suggested-by: Christophe JAILLET <[email protected]>
> Fixes: 81819f0fc828 ("SLUB core")
> Signed-off-by: Chao Yu <[email protected]>
> ---
> mm/slub.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 5ba6db62a5ab..a045c1ca8772 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -5883,7 +5883,7 @@ static inline struct kset *cache_kset(struct kmem_cache *s)
> return slab_kset;
> }
>
> -#define ID_STR_LENGTH 64
> +#define ID_STR_LENGTH 32
>
> /* Create a unique string id for a slab cache:
> *
> @@ -5919,7 +5919,10 @@ static char *create_unique_id(struct kmem_cache *s)
> *p++ = '-';
> p += sprintf(p, "%07u", s->size);
>
> - BUG_ON(p > name + ID_STR_LENGTH - 1);
> + if (p > name + ID_STR_LENGTH - 1) {
> + kfree(name);
> + return ERR_PTR(-EINVAL);
> + }
> return name;
IIUC 16 bytes will be still safe ;)
Anyway, for either size:
Looks good to me,
Reviewed-by: Hyeonggon Yoo <[email protected]>
Thanks!
> }
>
> --
> 2.25.1
>
--
Thanks,
Hyeonggon
On 9/18/22 11:21, Chao Yu wrote:
> From: Chao Yu <[email protected]>
>
> As Christophe JAILLET suggested:
>
> In create_unique_id(),
>
> "looks that ID_STR_LENGTH could even be reduced to 32 or 16.
>
> The 2nd BUG_ON at the end of the function could certainly be just
> removed as well or remplaced by a:
> if (p > name + ID_STR_LENGTH - 1) {
> kfree(name);
> return -E<something>;
> }
> "
>
> According to above suggestion, let's do below cleanups:
> 1. reduce ID_STR_LENGTH to 32, as the buffer size should be enough;
> 2. remove BUG_ON() and return error if check condition is true.
I'd leave a WARN_ON there as we really don't expect this to happen, so if it
does, we should be loud about it and not silently fail.
> Link: https://lore.kernel.org/linux-mm/[email protected]/
> Suggested-by: Christophe JAILLET <[email protected]>
> Fixes: 81819f0fc828 ("SLUB core")
> Signed-off-by: Chao Yu <[email protected]>
> ---
> mm/slub.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 5ba6db62a5ab..a045c1ca8772 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -5883,7 +5883,7 @@ static inline struct kset *cache_kset(struct kmem_cache *s)
> return slab_kset;
> }
>
> -#define ID_STR_LENGTH 64
> +#define ID_STR_LENGTH 32
>
> /* Create a unique string id for a slab cache:
> *
> @@ -5919,7 +5919,10 @@ static char *create_unique_id(struct kmem_cache *s)
> *p++ = '-';
> p += sprintf(p, "%07u", s->size);
Hm but sprintf() will happily overflow, so if we only detect that
afterwards, it's kinda too late to gracefully fail.
Should use snprintf() then?
> - BUG_ON(p > name + ID_STR_LENGTH - 1);
> + if (p > name + ID_STR_LENGTH - 1) {
> + kfree(name);
> + return ERR_PTR(-EINVAL);
> + }
> return name;
> }
>
On 2022/9/23 4:47, Vlastimil Babka wrote:
> On 9/18/22 11:21, Chao Yu wrote:
>> From: Chao Yu <[email protected]>
>>
>> As Christophe JAILLET suggested:
>>
>> In create_unique_id(),
>>
>> "looks that ID_STR_LENGTH could even be reduced to 32 or 16.
>>
>> The 2nd BUG_ON at the end of the function could certainly be just
>> removed as well or remplaced by a:
>> if (p > name + ID_STR_LENGTH - 1) {
>> kfree(name);
>> return -E<something>;
>> }
>> "
>>
>> According to above suggestion, let's do below cleanups:
>> 1. reduce ID_STR_LENGTH to 32, as the buffer size should be enough;
>> 2. remove BUG_ON() and return error if check condition is true.
>
> I'd leave a WARN_ON there as we really don't expect this to happen, so if it
> does, we should be loud about it and not silently fail.
Agreed.
>
>> Link: https://lore.kernel.org/linux-mm/[email protected]/
>> Suggested-by: Christophe JAILLET <[email protected]>
>> Fixes: 81819f0fc828 ("SLUB core")
>> Signed-off-by: Chao Yu <[email protected]>
>> ---
>> mm/slub.c | 7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/slub.c b/mm/slub.c
>> index 5ba6db62a5ab..a045c1ca8772 100644
>> --- a/mm/slub.c
>> +++ b/mm/slub.c
>> @@ -5883,7 +5883,7 @@ static inline struct kset *cache_kset(struct kmem_cache *s)
>> return slab_kset;
>> }
>>
>> -#define ID_STR_LENGTH 64
>> +#define ID_STR_LENGTH 32
>>
>> /* Create a unique string id for a slab cache:
>> *
>> @@ -5919,7 +5919,10 @@ static char *create_unique_id(struct kmem_cache *s)
>> *p++ = '-';
>> p += sprintf(p, "%07u", s->size);
>
> Hm but sprintf() will happily overflow, so if we only detect that
> afterwards, it's kinda too late to gracefully fail.
> Should use snprintf() then?
Correct.
Updated in v2.
Thanks,
>
>> - BUG_ON(p > name + ID_STR_LENGTH - 1);
>> + if (p > name + ID_STR_LENGTH - 1) {
>> + kfree(name);
>> + return ERR_PTR(-EINVAL);
>> + }
>> return name;
>> }
>>
>