In vhost_commit(), it may happen that dev->mem_sections and
dev->tmp_sections are equal, in which case, unconditionally
freeing old_sections at the end of the function will also free
dev->mem_sections used on subsequent call leading to a segmentation
fault.
Check this situation before deallocating memory.
Signed-off-by: Eric Auger <eric.au...@redhat.com>
Fixes: c44317efecb2 ("vhost: Build temporary section list and deref
after commit")
CC: QEMU Stable <qemu-sta...@nongnu.org>
---
This SIGSEV condition can be reproduced with
https://lore.kernel.org/all/20230904080451.424731-1-eric.au...@redhat.com/#r
This is most probably happening in a situation where the memory API is
used in a wrong manner but well.
---
hw/virtio/vhost.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index e2f6ffb446..c02c599ef0 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -545,6 +545,11 @@ static void vhost_commit(MemoryListener *listener)
dev->mem_sections = dev->tmp_sections;
dev->n_mem_sections = dev->n_tmp_sections;
+ if (old_sections == dev->mem_sections) {
+ assert(n_old_sections == dev->n_mem_sections);
+ return;
+ }
+
if (dev->n_mem_sections != n_old_sections) {
changed = true;
} else {
--
2.41.0
