[PATCH] sfc: fix a double-free bug in efx_probe_filters

[PATCH] sfc: fix a double-free bug in efx_probe_filters

[Zhipeng Lu]

In efx_probe_filters, the channel->rps_flow_id is freed in a
efx_for_each_channel marco  when success equals to 0.
However, after the following call chain:

efx_probe_filters
  |-> ef100_net_open
        |-> ef100_net_stop
              |-> efx_remove_filters

The channel->rps_flow_id is freed again in the efx_for_each_channel of
efx_remove_filters, triggering a double-free bug.

Fixes: a9dc3d5612ce ("sfc_ef100: RX filter table management and related gubbins")
Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>
---
 drivers/net/ethernet/sfc/rx_common.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/sfc/rx_common.c b/drivers/net/ethernet/sfc/rx_common.c
index d2f35ee15eff..fac227d372db 100644
--- a/drivers/net/ethernet/sfc/rx_common.c
+++ b/drivers/net/ethernet/sfc/rx_common.c
@@ -823,8 +823,10 @@ int efx_probe_filters(struct efx_nic *efx)
 		}
 
 		if (!success) {
-			efx_for_each_channel(channel, efx)
+			efx_for_each_channel(channel, efx) {
 				kfree(channel->rps_flow_id);
+				channel->rps_flow_id = NULL;
+			}
 			efx->type->filter_table_remove(efx);
 			rc = -ENOMEM;
 			goto out_unlock;
-- 
2.34.1

Re: [PATCH] sfc: fix a double-free bug in efx_probe_filters

[Simon Horman]

On Thu, Dec 14, 2023 at 11:22:46PM +0800, Zhipeng Lu wrote:
> In efx_probe_filters, the channel->rps_flow_id is freed in a
> efx_for_each_channel marco  when success equals to 0.
> However, after the following call chain:
> 
> efx_probe_filters
>   |-> ef100_net_open
>         |-> ef100_net_stop
>               |-> efx_remove_filters

I think the call chain may be a bit more like:

ef100_net_open
  |-> efx_probe_filters
  |-> ef100_net_stop
        |-> efx_remove_filters

> 
> The channel->rps_flow_id is freed again in the efx_for_each_channel of
> efx_remove_filters, triggering a double-free bug.
> 
> Fixes: a9dc3d5612ce ("sfc_ef100: RX filter table management and related gubbins")
> Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>

The above nit not withstanding, I agree with your reasoning.
And that the problem was introduced in the cited commit.

Reviewed-by: Simon Horman <horms@kernel.org>

...

Re: [PATCH] sfc: fix a double-free bug in efx_probe_filters

[Paolo Abeni]

Hi,

On Thu, 2023-12-14 at 23:22 +0800, Zhipeng Lu wrote:
> In efx_probe_filters, the channel->rps_flow_id is freed in a
> efx_for_each_channel marco  when success equals to 0.
> However, after the following call chain:
> 
> efx_probe_filters
>   |-> ef100_net_open
>         |-> ef100_net_stop
>               |-> efx_remove_filters
> 
> The channel->rps_flow_id is freed again in the efx_for_each_channel of
> efx_remove_filters, triggering a double-free bug.
> 
> Fixes: a9dc3d5612ce ("sfc_ef100: RX filter table management and related gubbins")
> Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>

The patch LGTM, but could you please update the commit message as per
Simon's suggestions make it more consistent? You can retain Simon's RB
tag.

Thanks!

Paolo

Re: [PATCH] sfc: fix a double-free bug in efx_probe_filters

[Edward Cree]

On 14/12/2023 15:22, Zhipeng Lu wrote:
> In efx_probe_filters, the channel->rps_flow_id is freed in a
> efx_for_each_channel marco  when success equals to 0.
> However, after the following call chain:
> 
> efx_probe_filters
>   |-> ef100_net_open
>         |-> ef100_net_stop
>               |-> efx_remove_filters
> 
> The channel->rps_flow_id is freed again in the efx_for_each_channel of
> efx_remove_filters, triggering a double-free bug.
> 
> Fixes: a9dc3d5612ce ("sfc_ef100: RX filter table management and related gubbins")
> Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>

Subject line should probably say [PATCH net] to specify the tree.
Modulo that, and Simon's correction to the commit message,

Reviewed-by: Edward Cree <ecree.xilinx@gmail.com>

Re: Re: [PATCH] sfc: fix a double-free bug in efx_probe_filters

[alexious]

> On Thu, Dec 14, 2023 at 11:22:46PM +0800, Zhipeng Lu wrote:
> > In efx_probe_filters, the channel->rps_flow_id is freed in a
> > efx_for_each_channel marco  when success equals to 0.
> > However, after the following call chain:
> > 
> > efx_probe_filters
> >   |-> ef100_net_open
> >         |-> ef100_net_stop
> >               |-> efx_remove_filters
> 
> I think the call chain may be a bit more like:
> 
> ef100_net_open
>   |-> efx_probe_filters
>   |-> ef100_net_stop
>         |-> efx_remove_filters
> 
> > 
> > The channel->rps_flow_id is freed again in the efx_for_each_channel of
> > efx_remove_filters, triggering a double-free bug.
> > 
> > Fixes: a9dc3d5612ce ("sfc_ef100: RX filter table management and related gubbins")
> > Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>
> 
> The above nit not withstanding, I agree with your reasoning.
> And that the problem was introduced in the cited commit.
> 
> Reviewed-by: Simon Horman <horms@kernel.org>

Sorry for the call-chain's problem, I was not familiar with it at that time.
Thanks for Simon's correction. Appreciate!
I'll soon send a v2 patch with the corrected call-chain and RB tags.