On Tue, Jul 15, 2014 at 10:12 AM, Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote:
> On Wed, Jul 09, 2014 at 03:30:14PM +0400, Andrey Ryabinin wrote:
>> We need to manually unpoison rounded up allocation size for dname
>> to avoid kasan's reports in __d_lookup_rcu.
>> __d_lookup_rcu may validly read a little beyound allocated size.
>
> If it read a little beyond allocated size, IMHO, it is better to
> allocate correct size.
>
> kmalloc(name->len + 1, GFP_KERNEL); -->
> kmalloc(roundup(name->len + 1, sizeof(unsigned long ), GFP_KERNEL);
>
> Isn't it?
I absolutely agree!
> Thanks.
>
>>
>> Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
>> Signed-off-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
>> ---
>> fs/dcache.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/fs/dcache.c b/fs/dcache.c
>> index b7e8b20..dff64f2 100644
>> --- a/fs/dcache.c
>> +++ b/fs/dcache.c
>> @@ -38,6 +38,7 @@
>> #include <linux/prefetch.h>
>> #include <linux/ratelimit.h>
>> #include <linux/list_lru.h>
>> +#include <linux/kasan.h>
>> #include "internal.h"
>> #include "mount.h"
>>
>> @@ -1412,6 +1413,8 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
>> kmem_cache_free(dentry_cache, dentry);
>> return NULL;
>> }
>> + unpoison_shadow(dname,
>> + roundup(name->len + 1, sizeof(unsigned long)));
>> } else {
>> dname = dentry->d_iname;
>> }
>> --
>> 1.8.5.5
>>
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