Commit a6968f7a authored by Xiaoguang Wang's avatar Xiaoguang Wang Committed by Martin K. Petersen
Browse files

scsi: target: tcmu: Fix possible page UAF 

tcmu_try_get_data_page() looks up pages under cmdr_lock, but it does not
take refcount properly and just returns page pointer. When
tcmu_try_get_data_page() returns, the returned page may have been freed by
tcmu_blocks_release().

We need to get_page() under cmdr_lock to avoid concurrent
tcmu_blocks_release().

Link: https://lore.kernel.org/r/20220311132206.24515-1-xiaoguang.wang@linux.alibaba.com


Reviewed-by: default avatarBodo Stroesser <bostroesser@gmail.com>
Signed-off-by: default avatarXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent ebfe3e0c

drivers/target/target_core_user.c

+2 −1
Original line number Diff line number Diff line
@@ -1821,6 +1821,7 @@ 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;

	}
@@ -1877,6 +1878,7 @@ 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;
@@ -1887,7 +1889,6 @@ static vm_fault_t tcmu_vma_fault(struct vm_fault *vmf) 
			return VM_FAULT_SIGBUS;

	}



	get_page(page);

	vmf->page = page;

	return 0;

}