[PATCH net] net: sparx5: Fix use after free inside sparx5_del_mact_entry

[PATCH net] net: sparx5: Fix use after free inside sparx5_del_mact_entry

[Horatiu Vultur]

Based on the static analyzis of the code it looks like when an entry
from the MAC table was removed, the entry was still used after being
freed. More precise the vid of the mac_entry was used after calling
devm_kfree on the mac_entry.
The fix consists in first using the vid of the mac_entry to delete the
entry from the HW and after that to free it.

Fixes: b37a1bae742f ("net: sparx5: add mactable support")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
---
 drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c b/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c
index 4af285918ea2a..75868b3f548ec 100644
--- a/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c
@@ -347,10 +347,10 @@ int sparx5_del_mact_entry(struct sparx5 *sparx5,
 				 list) {
 		if ((vid == 0 || mact_entry->vid == vid) &&
 		    ether_addr_equal(addr, mact_entry->mac)) {
+			sparx5_mact_forget(sparx5, addr, mact_entry->vid);
+
 			list_del(&mact_entry->list);
 			devm_kfree(sparx5->dev, mact_entry);
-
-			sparx5_mact_forget(sparx5, addr, mact_entry->vid);
 		}
 	}
 	mutex_unlock(&sparx5->mact_lock);
-- 
2.34.1

Re: [PATCH net] net: sparx5: Fix use after free inside sparx5_del_mact_entry

[Simon Horman]

On Fri, Mar 01, 2024 at 09:06:08AM +0100, Horatiu Vultur wrote:
> Based on the static analyzis of the code it looks like when an entry
> from the MAC table was removed, the entry was still used after being
> freed. More precise the vid of the mac_entry was used after calling
> devm_kfree on the mac_entry.
> The fix consists in first using the vid of the mac_entry to delete the
> entry from the HW and after that to free it.
> 
> Fixes: b37a1bae742f ("net: sparx5: add mactable support")
> Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>

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

Re: [PATCH net] net: sparx5: Fix use after free inside sparx5_del_mact_entry

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Fri, 1 Mar 2024 09:06:08 +0100 you wrote:
> Based on the static analyzis of the code it looks like when an entry
> from the MAC table was removed, the entry was still used after being
> freed. More precise the vid of the mac_entry was used after calling
> devm_kfree on the mac_entry.
> The fix consists in first using the vid of the mac_entry to delete the
> entry from the HW and after that to free it.
> 
> [...]

Here is the summary with links:
  - [net] net: sparx5: Fix use after free inside sparx5_del_mact_entry
    https://git.kernel.org/netdev/net/c/89d72d4125e9

You are awesome, thank you!
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