From 4dc229df1ad9fdef66000f40ac1d824b2fb3e808 Mon Sep 17 00:00:00 2001 From: Chen Qun Date: Thu, 10 Feb 2022 21:50:28 +0800 Subject: [PATCH] bugfix: fix eventfds may double free when vm_id reused in ivshmem As the ivshmem Server-Client Protol describes, when a client disconnects from the server, server sends disconnect notifications to the other clients. And the other clients will free the eventfds of the disconnected client according to the client ID. If the client ID is reused, the eventfds may be double freed. It will be solved by setting eventfds to NULL after freeing and allocating memory for it when it's used. Signed-off-by: Peng Liang Signed-off-by: jiangdongxu --- ...fds-may-double-free-when-vm_id-reuse.patch | 48 +++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 bugfix-fix-eventfds-may-double-free-when-vm_id-reuse.patch diff --git a/bugfix-fix-eventfds-may-double-free-when-vm_id-reuse.patch b/bugfix-fix-eventfds-may-double-free-when-vm_id-reuse.patch new file mode 100644 index 0000000..5802835 --- /dev/null +++ b/bugfix-fix-eventfds-may-double-free-when-vm_id-reuse.patch @@ -0,0 +1,48 @@ +From 02a17066ac3dfb5e53b72b15a80643154990191b Mon Sep 17 00:00:00 2001 +From: jiangdongxu +Date: Thu, 10 Feb 2022 21:50:28 +0800 +Subject: [PATCH] bugfix: fix eventfds may double free when vm_id reused in + ivshmem + +As the ivshmem Server-Client Protol describes, when a +client disconnects from the server, server sends disconnect +notifications to the other clients. And the other clients +will free the eventfds of the disconnected client according +to the client ID. If the client ID is reused, the eventfds +may be double freed. + +It will be solved by setting eventfds to NULL after freeing +and allocating memory for it when it's used. + +Signed-off-by: Peng Liang +Signed-off-by: jiangdongxu +--- + hw/misc/ivshmem.c | 5 +++++ + 1 file changed, 5 insertions(+) + +diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c +index 1ba4a98377..05f06ed6cf 100644 +--- a/hw/misc/ivshmem.c ++++ b/hw/misc/ivshmem.c +@@ -400,6 +400,7 @@ static void close_peer_eventfds(IVShmemState *s, int posn) + } + + g_free(s->peers[posn].eventfds); ++ s->peers[posn].eventfds = NULL; + s->peers[posn].nb_eventfds = 0; + } + +@@ -530,6 +531,10 @@ static void process_msg_connect(IVShmemState *s, uint16_t posn, int fd, + close(fd); + return; + } ++ if (peer->eventfds == NULL) { ++ peer->eventfds = g_new0(EventNotifier, s->vectors); ++ peer->nb_eventfds = 0; ++ } + vector = peer->nb_eventfds++; + + IVSHMEM_DPRINTF("eventfds[%d][%d] = %d\n", posn, vector, fd); +-- +2.27.0 +