* [PATCH] ceph: avoid putting the realm twice when docoding snaps fails
@ 2022-11-07 7:17 xiubli
2022-11-07 10:39 ` Luís Henriques
2022-11-07 15:21 ` Ilya Dryomov
0 siblings, 2 replies; 5+ messages in thread
From: xiubli @ 2022-11-07 7:17 UTC (permalink / raw)
To: ceph-devel; +Cc: lhenriques, jlayton, mchangir, idryomov, Xiubo Li, stable
From: Xiubo Li <xiubli@redhat.com>
When decoding the snaps fails it maybe leaving the 'first_realm'
and 'realm' pointing to the same snaprealm memory. And then it'll
put it twice and could cause random use-after-free, BUG_ON, etc
issues.
Cc: stable@vger.kernel.org
URL: https://tracker.ceph.com/issues/57686
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
fs/ceph/snap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index 9bceed2ebda3..baf17df05107 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -849,10 +849,12 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
if (realm_to_rebuild && p >= e)
rebuild_snap_realms(realm_to_rebuild, &dirty_realms);
- if (!first_realm)
+ if (!first_realm) {
first_realm = realm;
- else
+ realm = NULL;
+ } else {
ceph_put_snap_realm(mdsc, realm);
+ }
if (p < e)
goto more;
--
2.31.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] ceph: avoid putting the realm twice when docoding snaps fails
2022-11-07 7:17 [PATCH] ceph: avoid putting the realm twice when docoding snaps fails xiubli
@ 2022-11-07 10:39 ` Luís Henriques
2022-11-07 10:58 ` Xiubo Li
2022-11-07 15:21 ` Ilya Dryomov
1 sibling, 1 reply; 5+ messages in thread
From: Luís Henriques @ 2022-11-07 10:39 UTC (permalink / raw)
To: xiubli; +Cc: ceph-devel, jlayton, mchangir, idryomov, stable
On Mon, Nov 07, 2022 at 03:17:59PM +0800, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
>
> When decoding the snaps fails it maybe leaving the 'first_realm'
> and 'realm' pointing to the same snaprealm memory. And then it'll
> put it twice and could cause random use-after-free, BUG_ON, etc
> issues.
>
> Cc: stable@vger.kernel.org
> URL: https://tracker.ceph.com/issues/57686
> Signed-off-by: Xiubo Li <xiubli@redhat.com>
> ---
> fs/ceph/snap.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
> index 9bceed2ebda3..baf17df05107 100644
> --- a/fs/ceph/snap.c
> +++ b/fs/ceph/snap.c
> @@ -849,10 +849,12 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
> if (realm_to_rebuild && p >= e)
> rebuild_snap_realms(realm_to_rebuild, &dirty_realms);
>
> - if (!first_realm)
> + if (!first_realm) {
> first_realm = realm;
> - else
> + realm = NULL;
> + } else {
> ceph_put_snap_realm(mdsc, realm);
> + }
>
> if (p < e)
> goto more;
> --
> 2.31.1
>
This patch looks correct to me. But I wonder if there's a deeper problem
there (probably not on the kernel client). Because the other question is:
why are we failing to decode the snaps? But I guess this fix is worth it
anyway.
Reviewed-by: Luís Henriques <lhenriques@suse.de>
Cheers,
--
Luís
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] ceph: avoid putting the realm twice when docoding snaps fails
2022-11-07 10:39 ` Luís Henriques
@ 2022-11-07 10:58 ` Xiubo Li
0 siblings, 0 replies; 5+ messages in thread
From: Xiubo Li @ 2022-11-07 10:58 UTC (permalink / raw)
To: Luís Henriques; +Cc: ceph-devel, jlayton, mchangir, idryomov, stable
On 07/11/2022 18:39, Luís Henriques wrote:
> On Mon, Nov 07, 2022 at 03:17:59PM +0800, xiubli@redhat.com wrote:
>> From: Xiubo Li <xiubli@redhat.com>
>>
>> When decoding the snaps fails it maybe leaving the 'first_realm'
>> and 'realm' pointing to the same snaprealm memory. And then it'll
>> put it twice and could cause random use-after-free, BUG_ON, etc
>> issues.
>>
>> Cc: stable@vger.kernel.org
>> URL: https://tracker.ceph.com/issues/57686
>> Signed-off-by: Xiubo Li <xiubli@redhat.com>
>> ---
>> fs/ceph/snap.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
>> index 9bceed2ebda3..baf17df05107 100644
>> --- a/fs/ceph/snap.c
>> +++ b/fs/ceph/snap.c
>> @@ -849,10 +849,12 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
>> if (realm_to_rebuild && p >= e)
>> rebuild_snap_realms(realm_to_rebuild, &dirty_realms);
>>
>> - if (!first_realm)
>> + if (!first_realm) {
>> first_realm = realm;
>> - else
>> + realm = NULL;
>> + } else {
>> ceph_put_snap_realm(mdsc, realm);
>> + }
>>
>> if (p < e)
>> goto more;
>> --
>> 2.31.1
>>
> This patch looks correct to me. But I wonder if there's a deeper problem
> there (probably not on the kernel client). Because the other question is:
> why are we failing to decode the snaps? But I guess this fix is worth it
> anyway.
Yeah, good question.
At the same time the MDS also crashed [1][2] just before the kernel
crash was triggered seconds later. And the metadata in cephfs was
corrupted due to some reasons.
[1] https://tracker.ceph.com/issues/56140
[2] https://tracker.ceph.com/issues/54546
Thanks!
- Xiubo
> Reviewed-by: Luís Henriques <lhenriques@suse.de>
>
>
> Cheers,
> --
> Luís
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] ceph: avoid putting the realm twice when docoding snaps fails
2022-11-07 7:17 [PATCH] ceph: avoid putting the realm twice when docoding snaps fails xiubli
2022-11-07 10:39 ` Luís Henriques
@ 2022-11-07 15:21 ` Ilya Dryomov
2022-11-08 2:24 ` Xiubo Li
1 sibling, 1 reply; 5+ messages in thread
From: Ilya Dryomov @ 2022-11-07 15:21 UTC (permalink / raw)
To: xiubli; +Cc: ceph-devel, lhenriques, jlayton, mchangir, stable
On Mon, Nov 7, 2022 at 8:18 AM <xiubli@redhat.com> wrote:
>
> From: Xiubo Li <xiubli@redhat.com>
>
> When decoding the snaps fails it maybe leaving the 'first_realm'
> and 'realm' pointing to the same snaprealm memory. And then it'll
> put it twice and could cause random use-after-free, BUG_ON, etc
> issues.
>
> Cc: stable@vger.kernel.org
> URL: https://tracker.ceph.com/issues/57686
> Signed-off-by: Xiubo Li <xiubli@redhat.com>
> ---
> fs/ceph/snap.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
> index 9bceed2ebda3..baf17df05107 100644
> --- a/fs/ceph/snap.c
> +++ b/fs/ceph/snap.c
> @@ -849,10 +849,12 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
> if (realm_to_rebuild && p >= e)
> rebuild_snap_realms(realm_to_rebuild, &dirty_realms);
>
> - if (!first_realm)
> + if (!first_realm) {
> first_realm = realm;
> - else
> + realm = NULL;
Hi Xiubo,
I wonder why realm is cleared only in !first_realm branch? Can't
the same issue occur with realm?
first_realm is already set, ceph_put_snap_realm(realm)
p < e, goto more
decoding fails, goto bad
realm is still set and not IS_ERR, ceph_put_snap_realm(realm)
<realm is put twice>
Thanks,
Ilya
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] ceph: avoid putting the realm twice when docoding snaps fails
2022-11-07 15:21 ` Ilya Dryomov
@ 2022-11-08 2:24 ` Xiubo Li
0 siblings, 0 replies; 5+ messages in thread
From: Xiubo Li @ 2022-11-08 2:24 UTC (permalink / raw)
To: Ilya Dryomov; +Cc: ceph-devel, lhenriques, jlayton, mchangir, stable
On 07/11/2022 23:21, Ilya Dryomov wrote:
> On Mon, Nov 7, 2022 at 8:18 AM <xiubli@redhat.com> wrote:
>> From: Xiubo Li <xiubli@redhat.com>
>>
>> When decoding the snaps fails it maybe leaving the 'first_realm'
>> and 'realm' pointing to the same snaprealm memory. And then it'll
>> put it twice and could cause random use-after-free, BUG_ON, etc
>> issues.
>>
>> Cc: stable@vger.kernel.org
>> URL: https://tracker.ceph.com/issues/57686
>> Signed-off-by: Xiubo Li <xiubli@redhat.com>
>> ---
>> fs/ceph/snap.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
>> index 9bceed2ebda3..baf17df05107 100644
>> --- a/fs/ceph/snap.c
>> +++ b/fs/ceph/snap.c
>> @@ -849,10 +849,12 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
>> if (realm_to_rebuild && p >= e)
>> rebuild_snap_realms(realm_to_rebuild, &dirty_realms);
>>
>> - if (!first_realm)
>> + if (!first_realm) {
>> first_realm = realm;
>> - else
>> + realm = NULL;
> Hi Xiubo,
>
> I wonder why realm is cleared only in !first_realm branch? Can't
> the same issue occur with realm?
>
> first_realm is already set, ceph_put_snap_realm(realm)
> p < e, goto more
> decoding fails, goto bad
> realm is still set and not IS_ERR, ceph_put_snap_realm(realm)
> <realm is put twice>
Yeah, makes sense.
I will fix this.
Thanks Ilya!
>
> Thanks,
>
> Ilya
>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-11-08 2:25 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2022-11-07 7:17 [PATCH] ceph: avoid putting the realm twice when docoding snaps fails xiubli
2022-11-07 10:39 ` Luís Henriques
2022-11-07 10:58 ` Xiubo Li
2022-11-07 15:21 ` Ilya Dryomov
2022-11-08 2:24 ` Xiubo Li
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