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scsi: target: tcmu: Fix possible page UAF

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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: Bodo Stroesser <bostroesser@gmail.com>
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Xiaoguang Wang 2022-03-11 21:22:05 +08:00 committed by Martin K. Petersen
parent ebfe3e0c5e
commit a6968f7a36
1 changed files with 2 additions and 1 deletions
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3
drivers/target/target_core_user.c
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@ -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;
}