* [PATCH net] tls: Fix context leak on tls_device_down
@ 2022-05-12 9:18 Maxim Mikityanskiy
2022-05-12 18:40 ` patchwork-bot+netdevbpf
0 siblings, 1 reply; 2+ messages in thread
From: Maxim Mikityanskiy @ 2022-05-12 9:18 UTC (permalink / raw)
To: Jakub Kicinski, David S. Miller, Daniel Borkmann, John Fastabend
Cc: Paolo Abeni, Boris Pismenny, Tariq Toukan, Eric Dumazet, netdev,
Maxim Mikityanskiy
The commit cited below claims to fix a use-after-free condition after
tls_device_down. Apparently, the description wasn't fully accurate. The
context stayed alive, but ctx->netdev became NULL, and the offload was
torn down without a proper fallback, so a bug was present, but a
different kind of bug.
Due to misunderstanding of the issue, the original patch dropped the
refcount_dec_and_test line for the context to avoid the alleged
premature deallocation. That line has to be restored, because it matches
the refcount_inc_not_zero from the same function, otherwise the contexts
that survived tls_device_down are leaked.
This patch fixes the described issue by restoring refcount_dec_and_test.
After this change, there is no leak anymore, and the fallback to
software kTLS still works.
Fixes: c55dcdd435aa ("net/tls: Fix use-after-free after the TLS device goes down and up")
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
---
net/tls/tls_device.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index af875ad4a822..3919fe2c58c5 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -1347,7 +1347,10 @@ static int tls_device_down(struct net_device *netdev)
/* Device contexts for RX and TX will be freed in on sk_destruct
* by tls_device_free_ctx. rx_conf and tx_conf stay in TLS_HW.
+ * Now release the ref taken above.
*/
+ if (refcount_dec_and_test(&ctx->refcount))
+ tls_device_free_ctx(ctx);
}
up_write(&device_offload_lock);
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net] tls: Fix context leak on tls_device_down
2022-05-12 9:18 [PATCH net] tls: Fix context leak on tls_device_down Maxim Mikityanskiy
@ 2022-05-12 18:40 ` patchwork-bot+netdevbpf
0 siblings, 0 replies; 2+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-05-12 18:40 UTC (permalink / raw)
To: Maxim Mikityanskiy
Cc: kuba, davem, daniel, john.fastabend, pabeni, borisp, tariqt,
edumazet, netdev
Hello:
This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:
On Thu, 12 May 2022 12:18:30 +0300 you wrote:
> The commit cited below claims to fix a use-after-free condition after
> tls_device_down. Apparently, the description wasn't fully accurate. The
> context stayed alive, but ctx->netdev became NULL, and the offload was
> torn down without a proper fallback, so a bug was present, but a
> different kind of bug.
>
> Due to misunderstanding of the issue, the original patch dropped the
> refcount_dec_and_test line for the context to avoid the alleged
> premature deallocation. That line has to be restored, because it matches
> the refcount_inc_not_zero from the same function, otherwise the contexts
> that survived tls_device_down are leaked.
>
> [...]
Here is the summary with links:
- [net] tls: Fix context leak on tls_device_down
https://git.kernel.org/netdev/net/c/3740651bf7e2
You are awesome, thank you!
--
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2022-05-12 18:40 ` patchwork-bot+netdevbpf
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