[Qemu-devel] [PATCH for-3.1] vfio-helpers: Fix qemu_vfio_open_pci() crash

[Markus Armbruster <armbru@redhat.com>]

qemu_vfio_open_common() initializes s->lock only after passing s to
qemu_vfio_dma_map() via qemu_vfio_init_ramblock().
qemu_vfio_dma_map() tries to lock the uninitialized lock and crashes.

Fix by initializing s->lock first.

RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1645840
Fixes: 418026ca43bc2626db092d7558258f9594366f28
Cc: qemu-stable@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
Compile-tested only, as I lack suitable hardware.  Cong Li (cc'ed) is
going to test it for real.  It looks obvious enough to me to put it
into -rc3 without waiting for the test results.  We can also wait and
put it into -rc4.

 util/vfio-helpers.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
index 1d9272efa4..cccc9cd42e 100644
--- a/util/vfio-helpers.c
+++ b/util/vfio-helpers.c
@@ -411,13 +411,13 @@ static int qemu_vfio_init_ramblock(const char *block_name, void *host_addr,
 
 static void qemu_vfio_open_common(QEMUVFIOState *s)
 {
+    qemu_mutex_init(&s->lock);
     s->ram_notifier.ram_block_added = qemu_vfio_ram_block_added;
     s->ram_notifier.ram_block_removed = qemu_vfio_ram_block_removed;
     ram_block_notifier_add(&s->ram_notifier);
     s->low_water_mark = QEMU_VFIO_IOVA_MIN;
     s->high_water_mark = QEMU_VFIO_IOVA_MAX;
     qemu_ram_foreach_block(qemu_vfio_init_ramblock, s);
-    qemu_mutex_init(&s->lock);
 }
 
 /**
-- 
2.17.2