From: Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx> [ Upstream commit a6968f7a367f128d120447360734344d5a3d5336 ] 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@xxxxxxxxxxxxxxxxx Reviewed-by: Bodo Stroesser <bostroesser@xxxxxxxxx> Signed-off-by: Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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 96601fda47b1..f687481ccfdc 100644 --- a/drivers/target/target_core_user.c +++ b/drivers/target/target_core_user.c @@ -1165,6 +1165,7 @@ static struct page *tcmu_try_get_block_page(struct tcmu_dev *udev, uint32_t dbi) mutex_lock(&udev->cmdr_lock); page = tcmu_get_block_page(udev, dbi); if (likely(page)) { + get_page(page); mutex_unlock(&udev->cmdr_lock); return page; } @@ -1233,6 +1234,7 @@ static int 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 dbi; @@ -1243,7 +1245,6 @@ static int tcmu_vma_fault(struct vm_fault *vmf) return VM_FAULT_NOPAGE; } - get_page(page); vmf->page = page; return 0; } -- 2.35.1
