tcmu_try_get_data_page() looks up pages under cmdr_lock, but it don't
take refcount properly and just return page pointer.
When tcmu_try_get_data_page() returns, the returned page may have been
freed by tcmu_blocks_release(), need to get_page() under cmdr_lock to
avoid concurrent tcmu_blocks_release().
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx>
---
drivers/target/target_core_user.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 7b2a89a67cdb..06a5c4086551 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -1820,6 +1820,7 @@ static struct page *tcmu_try_get_data_page(struct tcmu_dev *udev, uint32_t dpi)
mutex_lock(&udev->cmdr_lock);
page = xa_load(&udev->data_pages, dpi);
if (likely(page)) {
+ get_page(page);
mutex_unlock(&udev->cmdr_lock);
return page;
}
@@ -1876,6 +1877,7 @@ static vm_fault_t tcmu_vma_fault(struct vm_fault *vmf)
/* For the vmalloc()ed cmd area pages */
addr = (void *)(unsigned long)info->mem[mi].addr + offset;
page = vmalloc_to_page(addr);
+ get_page(page);
} else {
uint32_t dpi;
@@ -1886,7 +1888,6 @@ static vm_fault_t tcmu_vma_fault(struct vm_fault *vmf)
return VM_FAULT_SIGBUS;
}
- get_page(page);
vmf->page = page;
return 0;
}
--
2.14.4.44.g2045bb6
