6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ilya Dryomov idryomov@gmail.com
commit 076381c261374c587700b3accf410bdd2dba334e upstream.
The wait loop in __ceph_open_session() can race with the client receiving a new monmap or osdmap shortly after the initial map is received. Both ceph_monc_handle_map() and handle_one_map() install a new map immediately after freeing the old one
kfree(monc->monmap); monc->monmap = monmap;
ceph_osdmap_destroy(osdc->osdmap); osdc->osdmap = newmap;
under client->monc.mutex and client->osdc.lock respectively, but because neither is taken in have_mon_and_osd_map() it's possible for client->monc.monmap->epoch and client->osdc.osdmap->epoch arms in
client->monc.monmap && client->monc.monmap->epoch && client->osdc.osdmap && client->osdc.osdmap->epoch;
condition to dereference an already freed map. This happens to be reproducible with generic/395 and generic/397 with KASAN enabled:
BUG: KASAN: slab-use-after-free in have_mon_and_osd_map+0x56/0x70 Read of size 4 at addr ffff88811012d810 by task mount.ceph/13305 CPU: 2 UID: 0 PID: 13305 Comm: mount.ceph Not tainted 6.14.0-rc2-build2+ #1266 ... Call Trace: <TASK> have_mon_and_osd_map+0x56/0x70 ceph_open_session+0x182/0x290 ceph_get_tree+0x333/0x680 vfs_get_tree+0x49/0x180 do_new_mount+0x1a3/0x2d0 path_mount+0x6dd/0x730 do_mount+0x99/0xe0 __do_sys_mount+0x141/0x180 do_syscall_64+0x9f/0x100 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK>
Allocated by task 13305: ceph_osdmap_alloc+0x16/0x130 ceph_osdc_init+0x27a/0x4c0 ceph_create_client+0x153/0x190 create_fs_client+0x50/0x2a0 ceph_get_tree+0xff/0x680 vfs_get_tree+0x49/0x180 do_new_mount+0x1a3/0x2d0 path_mount+0x6dd/0x730 do_mount+0x99/0xe0 __do_sys_mount+0x141/0x180 do_syscall_64+0x9f/0x100 entry_SYSCALL_64_after_hwframe+0x76/0x7e
Freed by task 9475: kfree+0x212/0x290 handle_one_map+0x23c/0x3b0 ceph_osdc_handle_map+0x3c9/0x590 mon_dispatch+0x655/0x6f0 ceph_con_process_message+0xc3/0xe0 ceph_con_v1_try_read+0x614/0x760 ceph_con_workfn+0x2de/0x650 process_one_work+0x486/0x7c0 process_scheduled_works+0x73/0x90 worker_thread+0x1c8/0x2a0 kthread+0x2ec/0x300 ret_from_fork+0x24/0x40 ret_from_fork_asm+0x1a/0x30
Rewrite the wait loop to check the above condition directly with client->monc.mutex and client->osdc.lock taken as appropriate. While at it, improve the timeout handling (previously mount_timeout could be exceeded in case wait_event_interruptible_timeout() slept more than once) and access client->auth_err under client->monc.mutex to match how it's set in finish_auth().
monmap_show() and osdmap_show() now take the respective lock before accessing the map as well.
Cc: stable@vger.kernel.org Reported-by: David Howells dhowells@redhat.com Signed-off-by: Ilya Dryomov idryomov@gmail.com Reviewed-by: Viacheslav Dubeyko Slava.Dubeyko@ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ceph/ceph_common.c | 53 +++++++++++++++++++++++++++++-------------------- net/ceph/debugfs.c | 14 +++++++++--- 2 files changed, 42 insertions(+), 25 deletions(-)
--- a/net/ceph/ceph_common.c +++ b/net/ceph/ceph_common.c @@ -786,41 +786,52 @@ void ceph_reset_client_addr(struct ceph_ EXPORT_SYMBOL(ceph_reset_client_addr);
/* - * true if we have the mon map (and have thus joined the cluster) - */ -static bool have_mon_and_osd_map(struct ceph_client *client) -{ - return client->monc.monmap && client->monc.monmap->epoch && - client->osdc.osdmap && client->osdc.osdmap->epoch; -} - -/* * mount: join the ceph cluster, and open root directory. */ int __ceph_open_session(struct ceph_client *client, unsigned long started) { - unsigned long timeout = client->options->mount_timeout; - long err; + DEFINE_WAIT_FUNC(wait, woken_wake_function); + long timeout = ceph_timeout_jiffies(client->options->mount_timeout); + bool have_monmap, have_osdmap; + int err;
/* open session, and wait for mon and osd maps */ err = ceph_monc_open_session(&client->monc); if (err < 0) return err;
- while (!have_mon_and_osd_map(client)) { - if (timeout && time_after_eq(jiffies, started + timeout)) - return -ETIMEDOUT; + add_wait_queue(&client->auth_wq, &wait); + for (;;) { + mutex_lock(&client->monc.mutex); + err = client->auth_err; + have_monmap = client->monc.monmap && client->monc.monmap->epoch; + mutex_unlock(&client->monc.mutex); + + down_read(&client->osdc.lock); + have_osdmap = client->osdc.osdmap && client->osdc.osdmap->epoch; + up_read(&client->osdc.lock); + + if (err || (have_monmap && have_osdmap)) + break; + + if (signal_pending(current)) { + err = -ERESTARTSYS; + break; + } + + if (!timeout) { + err = -ETIMEDOUT; + break; + }
/* wait */ dout("mount waiting for mon_map\n"); - err = wait_event_interruptible_timeout(client->auth_wq, - have_mon_and_osd_map(client) || (client->auth_err < 0), - ceph_timeout_jiffies(timeout)); - if (err < 0) - return err; - if (client->auth_err < 0) - return client->auth_err; + timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, timeout); } + remove_wait_queue(&client->auth_wq, &wait); + + if (err) + return err;
pr_info("client%llu fsid %pU\n", ceph_client_gid(client), &client->fsid); --- a/net/ceph/debugfs.c +++ b/net/ceph/debugfs.c @@ -36,8 +36,9 @@ static int monmap_show(struct seq_file * int i; struct ceph_client *client = s->private;
+ mutex_lock(&client->monc.mutex); if (client->monc.monmap == NULL) - return 0; + goto out_unlock;
seq_printf(s, "epoch %d\n", client->monc.monmap->epoch); for (i = 0; i < client->monc.monmap->num_mon; i++) { @@ -48,6 +49,9 @@ static int monmap_show(struct seq_file * ENTITY_NAME(inst->name), ceph_pr_addr(&inst->addr)); } + +out_unlock: + mutex_unlock(&client->monc.mutex); return 0; }
@@ -56,13 +60,14 @@ static int osdmap_show(struct seq_file * int i; struct ceph_client *client = s->private; struct ceph_osd_client *osdc = &client->osdc; - struct ceph_osdmap *map = osdc->osdmap; + struct ceph_osdmap *map; struct rb_node *n;
+ down_read(&osdc->lock); + map = osdc->osdmap; if (map == NULL) - return 0; + goto out_unlock;
- down_read(&osdc->lock); seq_printf(s, "epoch %u barrier %u flags 0x%x\n", map->epoch, osdc->epoch_barrier, map->flags);
@@ -131,6 +136,7 @@ static int osdmap_show(struct seq_file * seq_printf(s, "]\n"); }
+out_unlock: up_read(&osdc->lock); return 0; }