CVS commit: src/sys/dev/pci

["Shoichi YAMAGUCHI" <yamaguchi%netbsd.org@localhost>]

Module Name:    src
Committed By:   yamaguchi
Date:           Fri Apr 21 02:17:32 UTC 2023

Modified Files:
        src/sys/dev/pci: virtio.c

Log Message:
virtio(4): change members of struct vring_desc_extra before free a slot

This prevents the following race condition.
1. Thread-A: calls virtio_dequeue_commit() and
             puts a slot into free descriptor chain in vq_free_slot()
2. Thread-B: calls virtio_enqueue_prep() and get the slot stored by Thread-A
3. Thread-B: calls virtio_enqueue_reserve() and
             changes desc_base and desc_free_idx for the slot
4. Thread-A: changes the same members updated by Thread-B

reported by hannken, thanks.


To generate a diff of this commit:
cvs rdiff -u -r1.77 -r1.78 src/sys/dev/pci/virtio.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.