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authorAlexey Khoroshilov <khoroshilov@ispras.ru>2018-07-06 23:50:06 +0300
committerAlex Williamson <alex.williamson@redhat.com>2018-07-11 13:22:41 -0600
commit498e8bf51c633cc4496343e6113f340f8e9301ae (patch)
tree43bdf27e23afef2d4c07e184372a979c3910ef7d
parent1e4b044d22517cae7047c99038abb444423243ca (diff)
sample: vfio-mdev: avoid deadlock in mdev_access()
mdev_access() calls mbochs_get_page() with mdev_state->ops_lock held, while mbochs_get_page() locks the mutex by itself. It leads to unavoidable deadlock. Found by Linux Driver Verification project (linuxtesting.org). Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
-rw-r--r--samples/vfio-mdev/mbochs.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index d5d5a499160c..2535c3677c7b 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -178,6 +178,8 @@ static const char *vbe_name(u32 index)
return "(invalid)";
}
+static struct page *__mbochs_get_page(struct mdev_state *mdev_state,
+ pgoff_t pgoff);
static struct page *mbochs_get_page(struct mdev_state *mdev_state,
pgoff_t pgoff);
@@ -394,7 +396,7 @@ static ssize_t mdev_access(struct mdev_device *mdev, char *buf, size_t count,
MBOCHS_MEMORY_BAR_OFFSET + mdev_state->memsize) {
pos -= MBOCHS_MMIO_BAR_OFFSET;
poff = pos & ~PAGE_MASK;
- pg = mbochs_get_page(mdev_state, pos >> PAGE_SHIFT);
+ pg = __mbochs_get_page(mdev_state, pos >> PAGE_SHIFT);
map = kmap(pg);
if (is_write)
memcpy(map + poff, buf, count);