* RE: [PATCH] net: rswitch: Avoid use-after-free in rswitch_poll()
2024-07-02 21:08 [PATCH] net: rswitch: Avoid use-after-free in rswitch_poll() Radu Rendec
@ 2024-07-02 23:59 ` Yoshihiro Shimoda
2024-07-03 6:31 ` Niklas Söderlund
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Yoshihiro Shimoda @ 2024-07-02 23:59 UTC (permalink / raw)
To: Radu Rendec, David S. Miller, Paolo Abeni
Cc: Niklas Söderlund, Jakub Kicinski, Simon Horman,
netdev@vger.kernel.org, linux-renesas-soc@vger.kernel.org
Hello Radu,
> From: Radu Rendec, Sent: Wednesday, July 3, 2024 6:09 AM
>
> The use-after-free is actually in rswitch_tx_free(), which is inlined in
> rswitch_poll(). Since `skb` and `gq->skbs[gq->dirty]` are in fact the
> same pointer, the skb is first freed using dev_kfree_skb_any(), then the
> value in skb->len is used to update the interface statistics.
>
> Let's move around the instructions to use skb->len before the skb is
> freed.
>
> This bug is trivial to reproduce using KFENCE. It will trigger a splat
> every few packets. A simple ARP request or ICMP echo request is enough.
>
> Signed-off-by: Radu Rendec <rrendec@redhat.com>
Thank you very much for your patch!
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Best regards,
Yoshihiro Shimoda
> ---
> drivers/net/ethernet/renesas/rswitch.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> index dcab638c57fe8..24c90d8f5a442 100644
> --- a/drivers/net/ethernet/renesas/rswitch.c
> +++ b/drivers/net/ethernet/renesas/rswitch.c
> @@ -871,13 +871,13 @@ static void rswitch_tx_free(struct net_device *ndev)
> dma_rmb();
> skb = gq->skbs[gq->dirty];
> if (skb) {
> + rdev->ndev->stats.tx_packets++;
> + rdev->ndev->stats.tx_bytes += skb->len;
> dma_unmap_single(ndev->dev.parent,
> gq->unmap_addrs[gq->dirty],
> skb->len, DMA_TO_DEVICE);
> dev_kfree_skb_any(gq->skbs[gq->dirty]);
> gq->skbs[gq->dirty] = NULL;
> - rdev->ndev->stats.tx_packets++;
> - rdev->ndev->stats.tx_bytes += skb->len;
> }
> desc->desc.die_dt = DT_EEMPTY;
> }
> --
> 2.45.2
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] net: rswitch: Avoid use-after-free in rswitch_poll()
2024-07-02 21:08 [PATCH] net: rswitch: Avoid use-after-free in rswitch_poll() Radu Rendec
2024-07-02 23:59 ` Yoshihiro Shimoda
@ 2024-07-03 6:31 ` Niklas Söderlund
2024-07-04 2:16 ` Jakub Kicinski
2024-07-04 2:30 ` patchwork-bot+netdevbpf
3 siblings, 0 replies; 5+ messages in thread
From: Niklas Söderlund @ 2024-07-03 6:31 UTC (permalink / raw)
To: Radu Rendec
Cc: Yoshihiro Shimoda, David S. Miller, Paolo Abeni, Jakub Kicinski,
Simon Horman, netdev, linux-renesas-soc
Hi Radu,
On 2024-07-02 17:08:37 -0400, Radu Rendec wrote:
> The use-after-free is actually in rswitch_tx_free(), which is inlined in
> rswitch_poll(). Since `skb` and `gq->skbs[gq->dirty]` are in fact the
> same pointer, the skb is first freed using dev_kfree_skb_any(), then the
> value in skb->len is used to update the interface statistics.
>
> Let's move around the instructions to use skb->len before the skb is
> freed.
>
> This bug is trivial to reproduce using KFENCE. It will trigger a splat
> every few packets. A simple ARP request or ICMP echo request is enough.
>
> Signed-off-by: Radu Rendec <rrendec@redhat.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> ---
> drivers/net/ethernet/renesas/rswitch.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> index dcab638c57fe8..24c90d8f5a442 100644
> --- a/drivers/net/ethernet/renesas/rswitch.c
> +++ b/drivers/net/ethernet/renesas/rswitch.c
> @@ -871,13 +871,13 @@ static void rswitch_tx_free(struct net_device *ndev)
> dma_rmb();
> skb = gq->skbs[gq->dirty];
> if (skb) {
> + rdev->ndev->stats.tx_packets++;
> + rdev->ndev->stats.tx_bytes += skb->len;
> dma_unmap_single(ndev->dev.parent,
> gq->unmap_addrs[gq->dirty],
> skb->len, DMA_TO_DEVICE);
> dev_kfree_skb_any(gq->skbs[gq->dirty]);
> gq->skbs[gq->dirty] = NULL;
> - rdev->ndev->stats.tx_packets++;
> - rdev->ndev->stats.tx_bytes += skb->len;
> }
> desc->desc.die_dt = DT_EEMPTY;
> }
> --
> 2.45.2
>
--
Kind Regards,
Niklas Söderlund
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] net: rswitch: Avoid use-after-free in rswitch_poll()
2024-07-02 21:08 [PATCH] net: rswitch: Avoid use-after-free in rswitch_poll() Radu Rendec
2024-07-02 23:59 ` Yoshihiro Shimoda
2024-07-03 6:31 ` Niklas Söderlund
@ 2024-07-04 2:16 ` Jakub Kicinski
2024-07-04 2:30 ` patchwork-bot+netdevbpf
3 siblings, 0 replies; 5+ messages in thread
From: Jakub Kicinski @ 2024-07-04 2:16 UTC (permalink / raw)
To: Radu Rendec
Cc: Yoshihiro Shimoda, David S. Miller, Paolo Abeni,
Niklas Söderlund, Simon Horman, netdev, linux-renesas-soc
On Tue, 2 Jul 2024 17:08:37 -0400 Radu Rendec wrote:
> The use-after-free is actually in rswitch_tx_free(), which is inlined in
> rswitch_poll(). Since `skb` and `gq->skbs[gq->dirty]` are in fact the
> same pointer, the skb is first freed using dev_kfree_skb_any(), then the
> value in skb->len is used to update the interface statistics.
>
> Let's move around the instructions to use skb->len before the skb is
> freed.
>
> This bug is trivial to reproduce using KFENCE. It will trigger a splat
> every few packets. A simple ARP request or ICMP echo request is enough.
Please remember to add a Fixes tag in the future. I added one when
applying.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] net: rswitch: Avoid use-after-free in rswitch_poll()
2024-07-02 21:08 [PATCH] net: rswitch: Avoid use-after-free in rswitch_poll() Radu Rendec
` (2 preceding siblings ...)
2024-07-04 2:16 ` Jakub Kicinski
@ 2024-07-04 2:30 ` patchwork-bot+netdevbpf
3 siblings, 0 replies; 5+ messages in thread
From: patchwork-bot+netdevbpf @ 2024-07-04 2:30 UTC (permalink / raw)
To: Radu Rendec
Cc: yoshihiro.shimoda.uh, davem, pabeni, niklas.soderlund+renesas,
kuba, horms, netdev, linux-renesas-soc
Hello:
This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Tue, 2 Jul 2024 17:08:37 -0400 you wrote:
> The use-after-free is actually in rswitch_tx_free(), which is inlined in
> rswitch_poll(). Since `skb` and `gq->skbs[gq->dirty]` are in fact the
> same pointer, the skb is first freed using dev_kfree_skb_any(), then the
> value in skb->len is used to update the interface statistics.
>
> Let's move around the instructions to use skb->len before the skb is
> freed.
>
> [...]
Here is the summary with links:
- net: rswitch: Avoid use-after-free in rswitch_poll()
https://git.kernel.org/netdev/net/c/9a0c28efeec6
You are awesome, thank you!
--
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^ permalink raw reply [flat|nested] 5+ messages in thread