* [PATCH v4] ceph: fix NULL pointer dereference for req->r_session
@ 2022-11-10 2:08 xiubli
2022-11-10 11:49 ` Ilya Dryomov
0 siblings, 1 reply; 3+ messages in thread
From: xiubli @ 2022-11-10 2:08 UTC (permalink / raw)
To: ceph-devel, idryomov; +Cc: lhenriques, jlayton, mchangir, Xiubo Li, stable
From: Xiubo Li <xiubli@redhat.com>
The request's r_session maybe changed when it was forwarded or
resent.
Cc: stable@vger.kernel.org
URL: https://bugzilla.redhat.com/show_bug.cgi?id=2137955
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
Changed in V4:
- move mdsc->mutex acquisition and max_sessions assignment into "if (req1 || req2)" branch
fs/ceph/caps.c | 54 +++++++++++++++-----------------------------------
1 file changed, 16 insertions(+), 38 deletions(-)
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 894adfb4a092..1c84be839087 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2297,7 +2297,6 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_mds_request *req1 = NULL, *req2 = NULL;
- unsigned int max_sessions;
int ret, err = 0;
spin_lock(&ci->i_unsafe_lock);
@@ -2315,28 +2314,24 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
}
spin_unlock(&ci->i_unsafe_lock);
- /*
- * The mdsc->max_sessions is unlikely to be changed
- * mostly, here we will retry it by reallocating the
- * sessions array memory to get rid of the mdsc->mutex
- * lock.
- */
-retry:
- max_sessions = mdsc->max_sessions;
-
/*
* Trigger to flush the journal logs in all the relevant MDSes
* manually, or in the worst case we must wait at most 5 seconds
* to wait the journal logs to be flushed by the MDSes periodically.
*/
- if ((req1 || req2) && likely(max_sessions)) {
- struct ceph_mds_session **sessions = NULL;
- struct ceph_mds_session *s;
+ if (req1 || req2) {
struct ceph_mds_request *req;
+ struct ceph_mds_session **sessions;
+ struct ceph_mds_session *s;
+ unsigned int max_sessions;
int i;
+ mutex_lock(&mdsc->mutex);
+ max_sessions = mdsc->max_sessions;
+
sessions = kcalloc(max_sessions, sizeof(s), GFP_KERNEL);
if (!sessions) {
+ mutex_unlock(&mdsc->mutex);
err = -ENOMEM;
goto out;
}
@@ -2346,18 +2341,8 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
list_for_each_entry(req, &ci->i_unsafe_dirops,
r_unsafe_dir_item) {
s = req->r_session;
- if (!s)
+ if (!s || unlikely(s->s_mds >= max_sessions))
continue;
- if (unlikely(s->s_mds >= max_sessions)) {
- spin_unlock(&ci->i_unsafe_lock);
- for (i = 0; i < max_sessions; i++) {
- s = sessions[i];
- if (s)
- ceph_put_mds_session(s);
- }
- kfree(sessions);
- goto retry;
- }
if (!sessions[s->s_mds]) {
s = ceph_get_mds_session(s);
sessions[s->s_mds] = s;
@@ -2368,18 +2353,8 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
list_for_each_entry(req, &ci->i_unsafe_iops,
r_unsafe_target_item) {
s = req->r_session;
- if (!s)
+ if (!s || unlikely(s->s_mds >= max_sessions))
continue;
- if (unlikely(s->s_mds >= max_sessions)) {
- spin_unlock(&ci->i_unsafe_lock);
- for (i = 0; i < max_sessions; i++) {
- s = sessions[i];
- if (s)
- ceph_put_mds_session(s);
- }
- kfree(sessions);
- goto retry;
- }
if (!sessions[s->s_mds]) {
s = ceph_get_mds_session(s);
sessions[s->s_mds] = s;
@@ -2391,11 +2366,14 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
/* the auth MDS */
spin_lock(&ci->i_ceph_lock);
if (ci->i_auth_cap) {
- s = ci->i_auth_cap->session;
- if (!sessions[s->s_mds])
- sessions[s->s_mds] = ceph_get_mds_session(s);
+ s = ci->i_auth_cap->session;
+ if (likely(s->s_mds < max_sessions) &&
+ !sessions[s->s_mds]) {
+ sessions[s->s_mds] = ceph_get_mds_session(s);
+ }
}
spin_unlock(&ci->i_ceph_lock);
+ mutex_unlock(&mdsc->mutex);
/* send flush mdlog request to MDSes */
for (i = 0; i < max_sessions; i++) {
--
2.31.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v4] ceph: fix NULL pointer dereference for req->r_session
2022-11-10 2:08 [PATCH v4] ceph: fix NULL pointer dereference for req->r_session xiubli
@ 2022-11-10 11:49 ` Ilya Dryomov
2022-11-10 12:44 ` Xiubo Li
0 siblings, 1 reply; 3+ messages in thread
From: Ilya Dryomov @ 2022-11-10 11:49 UTC (permalink / raw)
To: xiubli; +Cc: ceph-devel, lhenriques, jlayton, mchangir, stable
On Thu, Nov 10, 2022 at 3:08 AM <xiubli@redhat.com> wrote:
>
> From: Xiubo Li <xiubli@redhat.com>
>
> The request's r_session maybe changed when it was forwarded or
> resent.
>
> Cc: stable@vger.kernel.org
> URL: https://bugzilla.redhat.com/show_bug.cgi?id=2137955
> Signed-off-by: Xiubo Li <xiubli@redhat.com>
> ---
>
> Changed in V4:
> - move mdsc->mutex acquisition and max_sessions assignment into "if (req1 || req2)" branch
>
> fs/ceph/caps.c | 54 +++++++++++++++-----------------------------------
> 1 file changed, 16 insertions(+), 38 deletions(-)
>
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 894adfb4a092..1c84be839087 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -2297,7 +2297,6 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
> struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
> struct ceph_inode_info *ci = ceph_inode(inode);
> struct ceph_mds_request *req1 = NULL, *req2 = NULL;
> - unsigned int max_sessions;
> int ret, err = 0;
>
> spin_lock(&ci->i_unsafe_lock);
> @@ -2315,28 +2314,24 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
> }
> spin_unlock(&ci->i_unsafe_lock);
>
> - /*
> - * The mdsc->max_sessions is unlikely to be changed
> - * mostly, here we will retry it by reallocating the
> - * sessions array memory to get rid of the mdsc->mutex
> - * lock.
> - */
> -retry:
> - max_sessions = mdsc->max_sessions;
> -
> /*
> * Trigger to flush the journal logs in all the relevant MDSes
> * manually, or in the worst case we must wait at most 5 seconds
> * to wait the journal logs to be flushed by the MDSes periodically.
> */
> - if ((req1 || req2) && likely(max_sessions)) {
> - struct ceph_mds_session **sessions = NULL;
> - struct ceph_mds_session *s;
> + if (req1 || req2) {
> struct ceph_mds_request *req;
> + struct ceph_mds_session **sessions;
> + struct ceph_mds_session *s;
> + unsigned int max_sessions;
> int i;
>
> + mutex_lock(&mdsc->mutex);
> + max_sessions = mdsc->max_sessions;
> +
> sessions = kcalloc(max_sessions, sizeof(s), GFP_KERNEL);
> if (!sessions) {
> + mutex_unlock(&mdsc->mutex);
> err = -ENOMEM;
> goto out;
> }
> @@ -2346,18 +2341,8 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
> list_for_each_entry(req, &ci->i_unsafe_dirops,
> r_unsafe_dir_item) {
> s = req->r_session;
> - if (!s)
> + if (!s || unlikely(s->s_mds >= max_sessions))
Hi Xiubo,
I would be fine with this patch as is but I'm wondering if it can be
simplified further. Now that mdsc->mutex is held while sessions array
is populated, is checking s->s_mds against max_sessions actually
needed? Is it possible for some req->r_session on one of the unsafe
lists to have an "out of bounds" s_mds under mdsc->mutex?
Thanks,
Ilya
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v4] ceph: fix NULL pointer dereference for req->r_session
2022-11-10 11:49 ` Ilya Dryomov
@ 2022-11-10 12:44 ` Xiubo Li
0 siblings, 0 replies; 3+ messages in thread
From: Xiubo Li @ 2022-11-10 12:44 UTC (permalink / raw)
To: Ilya Dryomov; +Cc: ceph-devel, lhenriques, jlayton, mchangir, stable
On 10/11/2022 19:49, Ilya Dryomov wrote:
> On Thu, Nov 10, 2022 at 3:08 AM <xiubli@redhat.com> wrote:
>> From: Xiubo Li <xiubli@redhat.com>
>>
>> The request's r_session maybe changed when it was forwarded or
>> resent.
>>
>> Cc: stable@vger.kernel.org
>> URL: https://bugzilla.redhat.com/show_bug.cgi?id=2137955
>> Signed-off-by: Xiubo Li <xiubli@redhat.com>
>> ---
>>
>> Changed in V4:
>> - move mdsc->mutex acquisition and max_sessions assignment into "if (req1 || req2)" branch
>>
>> fs/ceph/caps.c | 54 +++++++++++++++-----------------------------------
>> 1 file changed, 16 insertions(+), 38 deletions(-)
>>
>> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
>> index 894adfb4a092..1c84be839087 100644
>> --- a/fs/ceph/caps.c
>> +++ b/fs/ceph/caps.c
>> @@ -2297,7 +2297,6 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
>> struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
>> struct ceph_inode_info *ci = ceph_inode(inode);
>> struct ceph_mds_request *req1 = NULL, *req2 = NULL;
>> - unsigned int max_sessions;
>> int ret, err = 0;
>>
>> spin_lock(&ci->i_unsafe_lock);
>> @@ -2315,28 +2314,24 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
>> }
>> spin_unlock(&ci->i_unsafe_lock);
>>
>> - /*
>> - * The mdsc->max_sessions is unlikely to be changed
>> - * mostly, here we will retry it by reallocating the
>> - * sessions array memory to get rid of the mdsc->mutex
>> - * lock.
>> - */
>> -retry:
>> - max_sessions = mdsc->max_sessions;
>> -
>> /*
>> * Trigger to flush the journal logs in all the relevant MDSes
>> * manually, or in the worst case we must wait at most 5 seconds
>> * to wait the journal logs to be flushed by the MDSes periodically.
>> */
>> - if ((req1 || req2) && likely(max_sessions)) {
>> - struct ceph_mds_session **sessions = NULL;
>> - struct ceph_mds_session *s;
>> + if (req1 || req2) {
>> struct ceph_mds_request *req;
>> + struct ceph_mds_session **sessions;
>> + struct ceph_mds_session *s;
>> + unsigned int max_sessions;
>> int i;
>>
>> + mutex_lock(&mdsc->mutex);
>> + max_sessions = mdsc->max_sessions;
>> +
>> sessions = kcalloc(max_sessions, sizeof(s), GFP_KERNEL);
>> if (!sessions) {
>> + mutex_unlock(&mdsc->mutex);
>> err = -ENOMEM;
>> goto out;
>> }
>> @@ -2346,18 +2341,8 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
>> list_for_each_entry(req, &ci->i_unsafe_dirops,
>> r_unsafe_dir_item) {
>> s = req->r_session;
>> - if (!s)
>> + if (!s || unlikely(s->s_mds >= max_sessions))
> Hi Xiubo,
>
> I would be fine with this patch as is but I'm wondering if it can be
> simplified further. Now that mdsc->mutex is held while sessions array
> is populated, is checking s->s_mds against max_sessions actually
> needed? Is it possible for some req->r_session on one of the unsafe
> lists to have an "out of bounds" s_mds under mdsc->mutex?
Yeah, this can be simplified.
Let me do that.
Thanks!
- Xiubo
>
> Thanks,
>
> Ilya
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-11-10 12:45 UTC | newest]
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2022-11-10 2:08 [PATCH v4] ceph: fix NULL pointer dereference for req->r_session xiubli
2022-11-10 11:49 ` Ilya Dryomov
2022-11-10 12:44 ` Xiubo Li
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