2023-09-13 18:39:44

by Ma Ke

Subject: [PATCH] net/qlcnic: fix possible use-after-free bugs in qlcnic_alloc_rx_skb()

In qlcnic_alloc_rx_skb(), when dma_map_single() fails, skb is freed
immediately. And skb could be freed again. This issue could allow a
local attacker to crash the system due to a use-after-free flaw.

Signed-off-by: Ma Ke <[email protected]>
---
drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c
index 41894d154013..6501aaf2b5ce 100644
--- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c
+++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c
@@ -832,6 +832,7 @@ static int qlcnic_alloc_rx_skb(struct qlcnic_adapter *adapter,
if (dma_mapping_error(&pdev->dev, dma)) {
adapter->stats.rx_dma_map_error++;
dev_kfree_skb_any(skb);
+ skb = NULL;
return -ENOMEM;
}

--
2.37.2

2023-09-15 05:46:19

by Simon Horman

Subject: Re: [PATCH] net/qlcnic: fix possible use-after-free bugs in qlcnic_alloc_rx_skb()

On Wed, Sep 13, 2023 at 06:41:19PM +0800, Ma Ke wrote:
> In qlcnic_alloc_rx_skb(), when dma_map_single() fails, skb is freed
> immediately. And skb could be freed again. This issue could allow a
> local attacker to crash the system due to a use-after-free flaw.
>
> Signed-off-by: Ma Ke <[email protected]>
> ---
> drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c
> index 41894d154013..6501aaf2b5ce 100644
> --- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c
> +++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c
> @@ -832,6 +832,7 @@ static int qlcnic_alloc_rx_skb(struct qlcnic_adapter *adapter,
> if (dma_mapping_error(&pdev->dev, dma)) {
> adapter->stats.rx_dma_map_error++;
> dev_kfree_skb_any(skb);
> + skb = NULL;
> return -ENOMEM;

Hi Ma Ke,

I am a unclear on how skb could be freed a second time.
skb is a local variable which goes out of scope when
the function returns.