Commit 498e8bf5 authored by Alexey Khoroshilov's avatar Alexey Khoroshilov Committed by Alex Williamson

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: default avatarAlexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 1e4b044d
...@@ -178,6 +178,8 @@ static const char *vbe_name(u32 index) ...@@ -178,6 +178,8 @@ static const char *vbe_name(u32 index)
return "(invalid)"; 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, static struct page *mbochs_get_page(struct mdev_state *mdev_state,
pgoff_t pgoff); pgoff_t pgoff);
...@@ -394,7 +396,7 @@ static ssize_t mdev_access(struct mdev_device *mdev, char *buf, size_t count, ...@@ -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) { MBOCHS_MEMORY_BAR_OFFSET + mdev_state->memsize) {
pos -= MBOCHS_MMIO_BAR_OFFSET; pos -= MBOCHS_MMIO_BAR_OFFSET;
poff = pos & ~PAGE_MASK; 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); map = kmap(pg);
if (is_write) if (is_write)
memcpy(map + poff, buf, count); memcpy(map + poff, buf, count);
......
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