From: Radoslaw Zarzynski <rzarzyns@redhat.com>
Date: Wed, 7 Apr 2021 19:48:49 +0000 (+0000)
Subject: crimson/osd: fix the lifetime of Notify during timeouts.
X-Git-Tag: v17.1.0~2317^2~1
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=aa4c90254e495840aef367b5d6144b2ea861e452;p=ceph.git

crimson/osd: fix the lifetime of Notify during timeouts.

This fixes a segfault during `LibRadosWatchNotify.WatchNotify2Timeout`.

Signed-off-by: Radoslaw Zarzynski <rzarzyns@redhat.com>
---

diff --git a/src/crimson/osd/watch.cc b/src/crimson/osd/watch.cc
index 8898be8bdf3a..ee9308e2858c 100644
--- a/src/crimson/osd/watch.cc
+++ b/src/crimson/osd/watch.cc
@@ -210,6 +210,10 @@ void Notify::do_timeout()
   if (complete) {
     return;
   }
+  // it might be that `this` is kept alive only because of the reference
+  // a watcher stores and which is being removed by `cancel_notify()`.
+  // to avoid use-after-free we bump up the ref counter with `guard_ptr`.
+  [[maybe_unused]] auto guard_ptr = shared_from_this();
   for (auto& watcher : watchers) {
     watcher->cancel_notify(ninfo.notify_id);
   }
diff --git a/src/crimson/osd/watch.h b/src/crimson/osd/watch.h
index c58cf3edd4a3..4b50d286050f 100644
--- a/src/crimson/osd/watch.h
+++ b/src/crimson/osd/watch.h
@@ -106,7 +106,7 @@ struct notify_reply_t {
 };
 std::ostream &operator<<(std::ostream &out, const notify_reply_t &rhs);
 
-class Notify {
+class Notify : public seastar::enable_shared_from_this<Notify> {
   std::set<WatchRef> watchers;
   const notify_info_t ninfo;
   crimson::net::ConnectionRef conn;