Messages in this thread Patch in this message | | | Date | Fri, 17 Nov 2023 14:14:31 +0800 | Subject | Re: [PATCH] ceph: quota: Fix invalid pointer access in | From | Xiubo Li <> |
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On 11/16/23 15:09, Wenchao Hao wrote: > On 2023/11/16 11:06, Xiubo Li wrote: >> >> On 11/16/23 10:54, Wenchao Hao wrote: >>> On 2023/11/15 21:34, Xiubo Li wrote: >>>> >>>> On 11/15/23 21:25, Ilya Dryomov wrote: >>>>> On Wed, Nov 15, 2023 at 2:17 PM Xiubo Li <xiubli@redhat.com> wrote: >>>>>> >>>>>> On 11/15/23 20:32, Ilya Dryomov wrote: >>>>>>> On Wed, Nov 15, 2023 at 1:35 AM Xiubo Li <xiubli@redhat.com> wrote: >>>>>>>> On 11/14/23 23:31, Wenchao Hao wrote: >>>>>>>>> This issue is reported by smatch, get_quota_realm() might return >>>>>>>>> ERR_PTR, so we should using IS_ERR_OR_NULL here to check the >>>>>>>>> return >>>>>>>>> value. >>>>>>>>> >>>>>>>>> Signed-off-by: Wenchao Hao <haowenchao2@huawei.com> >>>>>>>>> --- >>>>>>>>> fs/ceph/quota.c | 2 +- >>>>>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>>>>>> >>>>>>>>> diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c >>>>>>>>> index 9d36c3532de1..c4b2929c6a83 100644 >>>>>>>>> --- a/fs/ceph/quota.c >>>>>>>>> +++ b/fs/ceph/quota.c >>>>>>>>> @@ -495,7 +495,7 @@ bool ceph_quota_update_statfs(struct >>>>>>>>> ceph_fs_client *fsc, struct kstatfs *buf) >>>>>>>>> realm = get_quota_realm(mdsc, d_inode(fsc->sb->s_root), >>>>>>>>> QUOTA_GET_MAX_BYTES, true); >>>>>>>>> up_read(&mdsc->snap_rwsem); >>>>>>>>> - if (!realm) >>>>>>>>> + if (IS_ERR_OR_NULL(realm)) >>>>>>>>> return false; >>>>>>>>> >>>>>>>>> spin_lock(&realm->inodes_with_caps_lock); >>>>>>>> Good catch. >>>>>>>> >>>>>>>> Reviewed-by: Xiubo Li <xiubli@redhat.com> >>>>>>>> >>>>>>>> We should CC the stable mail list. >>>>>>> Hi Xiubo, >>>>>>> >>>>>>> What exactly is being fixed here? get_quota_realm() is called with >>>>>>> retry=true, which means that no errors can be returned -- >>>>>>> EAGAIN, the >>>>>>> only error that get_quota_realm() can otherwise generate, would be >>>>>>> handled internally by retrying. >>>>>> Yeah, that's true. >>>>>> >>>>>>> Am I missing something that makes this qualify for stable? >>>>>> Actually it's just for the smatch check for now. >>>>>> >>>>>> IMO we shouldn't depend on the 'retry', just potentially for new >>>>>> changes >>>>>> in future could return a ERR_PTR and cause potential bugs. >>>>> At present, ceph_quota_is_same_realm() also depends on it -- note how >>>>> old_realm isn't checked for errors at all and new_realm is only >>>>> checked >>>>> for EAGAIN there. >>>>> >>>>>> If that's not worth to make it for stable, let's remove it. >>>>> Yes, let's remove it. Please update the commit message as well, so >>>>> that it's clear that this is squashing a static checker warning and >>>>> doesn't actually fix any immediate bug. >>>> >>>> WenChao, >>>> >>>> Could update the commit comment and send the V2 ? >>>> >>> >>> OK, I would update the commit comment as following: >>> >>> This issue is reported by smatch, get_quota_realm() might return >>> ERR_PTR. It's not a immediate bug because get_quota_realm() is called >>> with 'retry=true', no errors can be returned. >>> >>> While we still should check the return value of get_quota_realm() with >>> IS_ERR_OR_NULL to avoid potential bugs if get_quota_realm() is changed >>> to return other ERR_PTR in future. >>> >>> What's more, should I change the ceph_quota_is_same_realm() too? >>> >> Yeah, please. Let's fix them all. >> > > is_same is return as true if both old_realm and new_realm are NULL, I > do not > want to change the origin logic except add check for ERR_PTR, so > following > is my change: > > 1. make sure xxx_realm is valid before calling ceph_put_snap_realm. > 2. return false if new_realm or old_realm is ERR_PTR, this is newly added > and now we would always run with the else branch. > > diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c > index c4b2929c6a83..8da9ffb05395 100644 > --- a/fs/ceph/quota.c > +++ b/fs/ceph/quota.c > @@ -290,16 +290,20 @@ bool ceph_quota_is_same_realm(struct inode *old, > struct inode *new) > new_realm = get_quota_realm(mdsc, new, QUOTA_GET_ANY, false); > if (PTR_ERR(new_realm) == -EAGAIN) { > up_read(&mdsc->snap_rwsem); > - if (old_realm) > + if (!IS_ERR_OR_NULL(old_realm)) > ceph_put_snap_realm(mdsc, old_realm); > goto restart; > } > - is_same = (old_realm == new_realm); > up_read(&mdsc->snap_rwsem); > > - if (old_realm) > + if (IS_ERR(new_realm)) > + is_same = false; > + else > + is_same = (old_realm == new_realm); > + > + if (!IS_ERR_OR_NULL(old_realm)) > ceph_put_snap_realm(mdsc, old_realm); > - if (new_realm) > + if (!IS_ERR_OR_NULL(new_realm)) > ceph_put_snap_realm(mdsc, new_realm); > > return is_same; > If we just to fix the smatch check, how about make get_quota_realm() to return a 'int' type value and at the same time add a 'realmp' parameter ? And just return '-EAGAIN' or '0' always.
Then it will be something likes:
diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c index c4b2929c6a83..f37f5324b6a1 100644 --- a/fs/ceph/quota.c +++ b/fs/ceph/quota.c @@ -211,10 +211,9 @@ void ceph_cleanup_quotarealms_inodes(struct ceph_mds_client *mdsc) * this function will return -EAGAIN; otherwise, the snaprealms walk-through * will be restarted. */ -static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc, - struct inode *inode, - enum quota_get_realm which_quota, - bool retry) +static int get_quota_realm(struct ceph_mds_client *mdsc, struct inode *inode, + enum quota_get_realm which_quota, + struct ceph_snap_realm **realmp, bool retry) { struct ceph_client *cl = mdsc->fsc->client; struct ceph_inode_info *ci = NULL; @@ -222,8 +221,10 @@ static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc, struct inode *in; bool has_quota;
+ if (realmp) + *realmp = NULL; if (ceph_snap(inode) != CEPH_NOSNAP) - return NULL; + return 0;
restart: realm = ceph_inode(inode)->i_snap_realm; @@ -250,7 +251,7 @@ static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc, break; ceph_put_snap_realm(mdsc, realm); if (!retry) - return ERR_PTR(-EAGAIN); + return -EAGAIN; goto restart; }
@@ -259,8 +260,11 @@ static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc, iput(in);
next = realm->parent; - if (has_quota || !next) - return realm; + if (has_quota || !next) { + if (realmp) + *realmp = realm; + return 0; + }
ceph_get_snap_realm(mdsc, next); ceph_put_snap_realm(mdsc, realm); @@ -269,14 +273,15 @@ static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc, if (realm) ceph_put_snap_realm(mdsc, realm);
- return NULL; + return 0; }
bool ceph_quota_is_same_realm(struct inode *old, struct inode *new) { struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(old->i_sb); - struct ceph_snap_realm *old_realm, *new_realm; + struct ceph_snap_realm *old_realm = NULL, *new_realm = NULL; bool is_same; + int ret;
restart: /* @@ -286,9 +291,9 @@ bool ceph_quota_is_same_realm(struct inode *old, struct inode *new) * dropped and we can then restart the whole operation. */ down_read(&mdsc->snap_rwsem); - old_realm = get_quota_realm(mdsc, old, QUOTA_GET_ANY, true); - new_realm = get_quota_realm(mdsc, new, QUOTA_GET_ANY, false); - if (PTR_ERR(new_realm) == -EAGAIN) { + get_quota_realm(mdsc, old, QUOTA_GET_ANY, &old_relam, true); + ret = get_quota_realm(mdsc, new, QUOTA_GET_ANY, &new_realm, false); + if (ret == -EAGAIN) { up_read(&mdsc->snap_rwsem); if (old_realm) ceph_put_snap_realm(mdsc, old_realm);
Won't be this better ?
Thanks
- Xiubo
> >> Thanks >> >> - Xiubo >> >> >>> Thanks >>> >>>> Thanks >>>> >>>> - Xiubo >>>> >>>> >>>>> Thanks, >>>>> >>>>> Ilya >>>>> >>>> >>> >> >> >
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