| Message ID | 20210128113250.60078-1-wanghai38@huawei.com |
|---|---|
| State | New |
| Headers | show |
| Series | Revert "mm/slub: fix a memory leak in sysfs_slab_add()" | expand |
On 1/28/21 12:32 PM, Wang Hai wrote: > This reverts commit dde3c6b72a16c2db826f54b2d49bdea26c3534a2. > > syzbot report a double-free bug. The following case can cause this bug. > - mm/slab_common.c: create_cache(): if the __kmem_cache_create() > fails, it does: > > out_free_cache: > kmem_cache_free(kmem_cache, s); > > - but __kmem_cache_create() - at least for slub() - will have done > > sysfs_slab_add(s) > -> sysfs_create_group() .. fails .. > -> kobject_del(&s->kobj); .. which frees s ... > > We can't remove the kmem_cache_free() in create_cache(), because > other error cases of __kmem_cache_create() do not free this. > > So, revert the commit dde3c6b72a16 ("mm/slub: fix a memory leak in > sysfs_slab_add()") to fix this. > > Reported-by: syzbot+d0bd96b4696c1ef67991@syzkaller.appspotmail.com > Fixes: dde3c6b72a16 ("mm/slub: fix a memory leak in sysfs_slab_add()") > Signed-off-by: Wang Hai <wanghai38@huawei.com> Cc: <stable@vger.kernel.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Double-free is worse than a rare small memory leak. Which would still be nice to fix, but I'm afraid it will be more complicated, so start with preventing the worse issue, including stable. > --- > mm/slub.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 69742ab9a21d..7ecbbbe5bc0c 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -5625,10 +5625,8 @@ static int sysfs_slab_add(struct kmem_cache *s) > > s->kobj.kset = kset; > err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name); > - if (err) { > - kobject_put(&s->kobj); > + if (err) > goto out; > - } > > err = sysfs_create_group(&s->kobj, &slab_attr_group); > if (err) >
diff --git a/mm/slub.c b/mm/slub.c index 69742ab9a21d..7ecbbbe5bc0c 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5625,10 +5625,8 @@ static int sysfs_slab_add(struct kmem_cache *s) s->kobj.kset = kset; err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name); - if (err) { - kobject_put(&s->kobj); + if (err) goto out; - } err = sysfs_create_group(&s->kobj, &slab_attr_group); if (err)
This reverts commit dde3c6b72a16c2db826f54b2d49bdea26c3534a2. syzbot report a double-free bug. The following case can cause this bug. - mm/slab_common.c: create_cache(): if the __kmem_cache_create() fails, it does: out_free_cache: kmem_cache_free(kmem_cache, s); - but __kmem_cache_create() - at least for slub() - will have done sysfs_slab_add(s) -> sysfs_create_group() .. fails .. -> kobject_del(&s->kobj); .. which frees s ... We can't remove the kmem_cache_free() in create_cache(), because other error cases of __kmem_cache_create() do not free this. So, revert the commit dde3c6b72a16 ("mm/slub: fix a memory leak in sysfs_slab_add()") to fix this. Reported-by: syzbot+d0bd96b4696c1ef67991@syzkaller.appspotmail.com Fixes: dde3c6b72a16 ("mm/slub: fix a memory leak in sysfs_slab_add()") Signed-off-by: Wang Hai <wanghai38@huawei.com> --- mm/slub.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)