This is a note to let you know that I've just added the patch titled
ceph: fix potential use-after-free bug when trimming caps
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ceph-fix-potential-use-after-free-bug-when-trimming-caps.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From aaf67de78807c59c35bafb5003d4fb457c764800 Mon Sep 17 00:00:00 2001
From: Xiubo Li <xiubli@xxxxxxxxxx>
Date: Wed, 19 Apr 2023 10:39:14 +0800
Subject: ceph: fix potential use-after-free bug when trimming caps
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From: Xiubo Li <xiubli@xxxxxxxxxx>
commit aaf67de78807c59c35bafb5003d4fb457c764800 upstream.
When trimming the caps and just after the 'session->s_cap_lock' is
released in ceph_iterate_session_caps() the cap maybe removed by
another thread, and when using the stale cap memory in the callbacks
it will trigger use-after-free crash.
We need to check the existence of the cap just after the 'ci->i_ceph_lock'
being acquired. And do nothing if it's already removed.
Cc: stable@xxxxxxxxxxxxxxx
Link: https://tracker.ceph.com/issues/43272
Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
Reviewed-by: Luís Henriques <lhenriques@xxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ceph/caps.c | 2 -
fs/ceph/debugfs.c | 16 +++++++----
fs/ceph/mds_client.c | 72 ++++++++++++++++++++++++++++++++-------------------
fs/ceph/mds_client.h | 3 --
fs/ceph/super.h | 2 +
5 files changed, 61 insertions(+), 34 deletions(-)
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -430,7 +430,7 @@ void ceph_reservation_status(struct ceph
*
* Called with i_ceph_lock held.
*/
-static struct ceph_cap *__get_cap_for_mds(struct ceph_inode_info *ci, int mds)
+struct ceph_cap *__get_cap_for_mds(struct ceph_inode_info *ci, int mds)
{
struct ceph_cap *cap;
struct rb_node *n = ci->i_caps.rb_node;
--- a/fs/ceph/debugfs.c
+++ b/fs/ceph/debugfs.c
@@ -248,14 +248,20 @@ static int metrics_caps_show(struct seq_
return 0;
}
-static int caps_show_cb(struct inode *inode, struct ceph_cap *cap, void *p)
+static int caps_show_cb(struct inode *inode, int mds, void *p)
{
+ struct ceph_inode_info *ci = ceph_inode(inode);
struct seq_file *s = p;
+ struct ceph_cap *cap;
- seq_printf(s, "0x%-17llx%-3d%-17s%-17s\n", ceph_ino(inode),
- cap->session->s_mds,
- ceph_cap_string(cap->issued),
- ceph_cap_string(cap->implemented));
+ spin_lock(&ci->i_ceph_lock);
+ cap = __get_cap_for_mds(ci, mds);
+ if (cap)
+ seq_printf(s, "0x%-17llx%-3d%-17s%-17s\n", ceph_ino(inode),
+ cap->session->s_mds,
+ ceph_cap_string(cap->issued),
+ ceph_cap_string(cap->implemented));
+ spin_unlock(&ci->i_ceph_lock);
return 0;
}
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1632,8 +1632,8 @@ static void cleanup_session_requests(str
* Caller must hold session s_mutex.
*/
int ceph_iterate_session_caps(struct ceph_mds_session *session,
- int (*cb)(struct inode *, struct ceph_cap *,
- void *), void *arg)
+ int (*cb)(struct inode *, int mds, void *),
+ void *arg)
{
struct list_head *p;
struct ceph_cap *cap;
@@ -1645,6 +1645,8 @@ int ceph_iterate_session_caps(struct cep
spin_lock(&session->s_cap_lock);
p = session->s_caps.next;
while (p != &session->s_caps) {
+ int mds;
+
cap = list_entry(p, struct ceph_cap, session_caps);
inode = igrab(&cap->ci->netfs.inode);
if (!inode) {
@@ -1652,6 +1654,7 @@ int ceph_iterate_session_caps(struct cep
continue;
}
session->s_cap_iterator = cap;
+ mds = cap->mds;
spin_unlock(&session->s_cap_lock);
if (last_inode) {
@@ -1663,7 +1666,7 @@ int ceph_iterate_session_caps(struct cep
old_cap = NULL;
}
- ret = cb(inode, cap, arg);
+ ret = cb(inode, mds, arg);
last_inode = inode;
spin_lock(&session->s_cap_lock);
@@ -1696,20 +1699,25 @@ out:
return ret;
}
-static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
- void *arg)
+static int remove_session_caps_cb(struct inode *inode, int mds, void *arg)
{
struct ceph_inode_info *ci = ceph_inode(inode);
bool invalidate = false;
- int iputs;
+ struct ceph_cap *cap;
+ int iputs = 0;
- dout("removing cap %p, ci is %p, inode is %p\n",
- cap, ci, &ci->netfs.inode);
spin_lock(&ci->i_ceph_lock);
- iputs = ceph_purge_inode_cap(inode, cap, &invalidate);
+ cap = __get_cap_for_mds(ci, mds);
+ if (cap) {
+ dout(" removing cap %p, ci is %p, inode is %p\n",
+ cap, ci, &ci->netfs.inode);
+
+ iputs = ceph_purge_inode_cap(inode, cap, &invalidate);
+ }
spin_unlock(&ci->i_ceph_lock);
- wake_up_all(&ci->i_cap_wq);
+ if (cap)
+ wake_up_all(&ci->i_cap_wq);
if (invalidate)
ceph_queue_invalidate(inode);
while (iputs--)
@@ -1780,8 +1788,7 @@ enum {
*
* caller must hold s_mutex.
*/
-static int wake_up_session_cb(struct inode *inode, struct ceph_cap *cap,
- void *arg)
+static int wake_up_session_cb(struct inode *inode, int mds, void *arg)
{
struct ceph_inode_info *ci = ceph_inode(inode);
unsigned long ev = (unsigned long)arg;
@@ -1792,12 +1799,14 @@ static int wake_up_session_cb(struct ino
ci->i_requested_max_size = 0;
spin_unlock(&ci->i_ceph_lock);
} else if (ev == RENEWCAPS) {
- if (cap->cap_gen < atomic_read(&cap->session->s_cap_gen)) {
- /* mds did not re-issue stale cap */
- spin_lock(&ci->i_ceph_lock);
+ struct ceph_cap *cap;
+
+ spin_lock(&ci->i_ceph_lock);
+ cap = __get_cap_for_mds(ci, mds);
+ /* mds did not re-issue stale cap */
+ if (cap && cap->cap_gen < atomic_read(&cap->session->s_cap_gen))
cap->issued = cap->implemented = CEPH_CAP_PIN;
- spin_unlock(&ci->i_ceph_lock);
- }
+ spin_unlock(&ci->i_ceph_lock);
} else if (ev == FORCE_RO) {
}
wake_up_all(&ci->i_cap_wq);
@@ -1959,16 +1968,22 @@ out:
* Yes, this is a bit sloppy. Our only real goal here is to respond to
* memory pressure from the MDS, though, so it needn't be perfect.
*/
-static int trim_caps_cb(struct inode *inode, struct ceph_cap *cap, void *arg)
+static int trim_caps_cb(struct inode *inode, int mds, void *arg)
{
int *remaining = arg;
struct ceph_inode_info *ci = ceph_inode(inode);
int used, wanted, oissued, mine;
+ struct ceph_cap *cap;
if (*remaining <= 0)
return -1;
spin_lock(&ci->i_ceph_lock);
+ cap = __get_cap_for_mds(ci, mds);
+ if (!cap) {
+ spin_unlock(&ci->i_ceph_lock);
+ return 0;
+ }
mine = cap->issued | cap->implemented;
used = __ceph_caps_used(ci);
wanted = __ceph_caps_file_wanted(ci);
@@ -3911,26 +3926,22 @@ out_unlock:
/*
* Encode information about a cap for a reconnect with the MDS.
*/
-static int reconnect_caps_cb(struct inode *inode, struct ceph_cap *cap,
- void *arg)
+static int reconnect_caps_cb(struct inode *inode, int mds, void *arg)
{
union {
struct ceph_mds_cap_reconnect v2;
struct ceph_mds_cap_reconnect_v1 v1;
} rec;
- struct ceph_inode_info *ci = cap->ci;
+ struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_reconnect_state *recon_state = arg;
struct ceph_pagelist *pagelist = recon_state->pagelist;
struct dentry *dentry;
+ struct ceph_cap *cap;
char *path;
- int pathlen = 0, err;
+ int pathlen = 0, err = 0;
u64 pathbase;
u64 snap_follows;
- dout(" adding %p ino %llx.%llx cap %p %lld %s\n",
- inode, ceph_vinop(inode), cap, cap->cap_id,
- ceph_cap_string(cap->issued));
-
dentry = d_find_primary(inode);
if (dentry) {
/* set pathbase to parent dir when msg_version >= 2 */
@@ -3947,6 +3958,15 @@ static int reconnect_caps_cb(struct inod
}
spin_lock(&ci->i_ceph_lock);
+ cap = __get_cap_for_mds(ci, mds);
+ if (!cap) {
+ spin_unlock(&ci->i_ceph_lock);
+ goto out_err;
+ }
+ dout(" adding %p ino %llx.%llx cap %p %lld %s\n",
+ inode, ceph_vinop(inode), cap, cap->cap_id,
+ ceph_cap_string(cap->issued));
+
cap->seq = 0; /* reset cap seq */
cap->issue_seq = 0; /* and issue_seq */
cap->mseq = 0; /* and migrate_seq */
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -541,8 +541,7 @@ extern void ceph_flush_cap_releases(stru
extern void ceph_queue_cap_reclaim_work(struct ceph_mds_client *mdsc);
extern void ceph_reclaim_caps_nr(struct ceph_mds_client *mdsc, int nr);
extern int ceph_iterate_session_caps(struct ceph_mds_session *session,
- int (*cb)(struct inode *,
- struct ceph_cap *, void *),
+ int (*cb)(struct inode *, int mds, void *),
void *arg);
extern void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc);
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -1192,6 +1192,8 @@ extern void ceph_kick_flushing_caps(stru
struct ceph_mds_session *session);
void ceph_kick_flushing_inode_caps(struct ceph_mds_session *session,
struct ceph_inode_info *ci);
+extern struct ceph_cap *__get_cap_for_mds(struct ceph_inode_info *ci,
+ int mds);
extern struct ceph_cap *ceph_get_cap_for_mds(struct ceph_inode_info *ci,
int mds);
extern void ceph_take_cap_refs(struct ceph_inode_info *ci, int caps,
Patches currently in stable-queue which might be from xiubli@xxxxxxxxxx are
queue-6.2/ceph-fix-potential-use-after-free-bug-when-trimming-caps.patch
