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authorLaurent Vivier <lvivier@redhat.com>2020-07-07 20:45:14 +0200
committerJason Wang <jasowang@redhat.com>2020-07-15 21:00:13 +0800
commit894022e616016fe81745753f14adfbd680a1c7ee (patch)
treefe44283139cd96b578d41ac420dfb06ec7efa7f6 /util
parent2b28a7ef90d79ed757f6b1cc512840389dc25748 (diff)
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net: check if the file descriptor is valid before using it
qemu_set_nonblock() checks that the file descriptor can be used and, if not, crashes QEMU. An assert() is used for that. The use of assert() is used to detect programming error and the coredump will allow to debug the problem. But in the case of the tap device, this assert() can be triggered by a misconfiguration by the user. At startup, it's not a real problem, but it can also happen during the hot-plug of a new device, and here it's a problem because we can crash a perfectly healthy system. For instance: # ip link add link virbr0 name macvtap0 type macvtap mode bridge # ip link set macvtap0 up # TAP=/dev/tap$(ip -o link show macvtap0 | cut -d: -f1) # qemu-system-x86_64 -machine q35 -device pcie-root-port,id=pcie-root-port-0 -monitor stdio 9<> $TAP (qemu) netdev_add type=tap,id=hostnet0,vhost=on,fd=9 (qemu) device_add driver=virtio-net-pci,netdev=hostnet0,id=net0,bus=pcie-root-port-0 (qemu) device_del net0 (qemu) netdev_del hostnet0 (qemu) netdev_add type=tap,id=hostnet1,vhost=on,fd=9 qemu-system-x86_64: .../util/oslib-posix.c:247: qemu_set_nonblock: Assertion `f != -1' failed. Aborted (core dumped) To avoid that, add a function, qemu_try_set_nonblock(), that allows to report the problem without crashing. In the same way, we also update the function for vhostfd in net_init_tap_one() and for fd in net_init_socket() (both descriptors are provided by the user and can be wrong). Signed-off-by: Laurent Vivier <lvivier@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
Diffstat (limited to 'util')
-rw-r--r--util/oslib-posix.c26
-rw-r--r--util/oslib-win32.c57
2 files changed, 50 insertions, 33 deletions
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index e60aea8..36bf859 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -260,25 +260,35 @@ void qemu_set_block(int fd)
assert(f != -1);
}
-void qemu_set_nonblock(int fd)
+int qemu_try_set_nonblock(int fd)
{
int f;
f = fcntl(fd, F_GETFL);
- assert(f != -1);
- f = fcntl(fd, F_SETFL, f | O_NONBLOCK);
-#ifdef __OpenBSD__
if (f == -1) {
+ return -errno;
+ }
+ if (fcntl(fd, F_SETFL, f | O_NONBLOCK) == -1) {
+#ifdef __OpenBSD__
/*
* Previous to OpenBSD 6.3, fcntl(F_SETFL) is not permitted on
* memory devices and sets errno to ENODEV.
* It's OK if we fail to set O_NONBLOCK on devices like /dev/null,
* because they will never block anyway.
*/
- assert(errno == ENODEV);
- }
-#else
- assert(f != -1);
+ if (errno == ENODEV) {
+ return 0;
+ }
#endif
+ return -errno;
+ }
+ return 0;
+}
+
+void qemu_set_nonblock(int fd)
+{
+ int f;
+ f = qemu_try_set_nonblock(fd);
+ assert(f == 0);
}
int socket_set_fast_reuse(int fd)
diff --git a/util/oslib-win32.c b/util/oslib-win32.c
index 3b49d27..7eedbe5 100644
--- a/util/oslib-win32.c
+++ b/util/oslib-win32.c
@@ -132,31 +132,6 @@ struct tm *localtime_r(const time_t *timep, struct tm *result)
}
#endif /* CONFIG_LOCALTIME_R */
-void qemu_set_block(int fd)
-{
- unsigned long opt = 0;
- WSAEventSelect(fd, NULL, 0);
- ioctlsocket(fd, FIONBIO, &opt);
-}
-
-void qemu_set_nonblock(int fd)
-{
- unsigned long opt = 1;
- ioctlsocket(fd, FIONBIO, &opt);
- qemu_fd_register(fd);
-}
-
-int socket_set_fast_reuse(int fd)
-{
- /* Enabling the reuse of an endpoint that was used by a socket still in
- * TIME_WAIT state is usually performed by setting SO_REUSEADDR. On Windows
- * fast reuse is the default and SO_REUSEADDR does strange things. So we
- * don't have to do anything here. More info can be found at:
- * http://msdn.microsoft.com/en-us/library/windows/desktop/ms740621.aspx */
- return 0;
-}
-
-
static int socket_error(void)
{
switch (WSAGetLastError()) {
@@ -233,6 +208,38 @@ static int socket_error(void)
}
}
+void qemu_set_block(int fd)
+{
+ unsigned long opt = 0;
+ WSAEventSelect(fd, NULL, 0);
+ ioctlsocket(fd, FIONBIO, &opt);
+}
+
+int qemu_try_set_nonblock(int fd)
+{
+ unsigned long opt = 1;
+ if (ioctlsocket(fd, FIONBIO, &opt) != NO_ERROR) {
+ return -socket_error();
+ }
+ qemu_fd_register(fd);
+ return 0;
+}
+
+void qemu_set_nonblock(int fd)
+{
+ (void)qemu_try_set_nonblock(fd);
+}
+
+int socket_set_fast_reuse(int fd)
+{
+ /* Enabling the reuse of an endpoint that was used by a socket still in
+ * TIME_WAIT state is usually performed by setting SO_REUSEADDR. On Windows
+ * fast reuse is the default and SO_REUSEADDR does strange things. So we
+ * don't have to do anything here. More info can be found at:
+ * http://msdn.microsoft.com/en-us/library/windows/desktop/ms740621.aspx */
+ return 0;
+}
+
int inet_aton(const char *cp, struct in_addr *ia)
{
uint32_t addr = inet_addr(cp);