[PATCH net] net/tls: fix page double free on TX cleanup

[PATCH net] net/tls: fix page double free on TX cleanup

[Jakub Kicinski]

From: Dirk van der Merwe <dirk.vandermerwe@netronome.com>

With commit 94850257cf0f ("tls: Fix tls_device handling of partial records")
a new path was introduced to cleanup partial records during sk_proto_close.
This path does not handle the SW KTLS tx_list cleanup.

This is unnecessary though since the free_resources calls for both
SW and offload paths will cleanup a partial record.

The visible effect is the following warning, but this bug also causes
a page double free.

    WARNING: CPU: 7 PID: 4000 at net/core/stream.c:206 sk_stream_kill_queues+0x103/0x110
    RIP: 0010:sk_stream_kill_queues+0x103/0x110
    RSP: 0018:ffffb6df87e07bd0 EFLAGS: 00010206
    RAX: 0000000000000000 RBX: ffff8c21db4971c0 RCX: 0000000000000007
    RDX: ffffffffffffffa0 RSI: 000000000000001d RDI: ffff8c21db497270
    RBP: ffff8c21db497270 R08: ffff8c29f4748600 R09: 000000010020001a
    R10: ffffb6df87e07aa0 R11: ffffffff9a445600 R12: 0000000000000007
    R13: 0000000000000000 R14: ffff8c21f03f2900 R15: ffff8c21f03b8df0
    Call Trace:
     inet_csk_destroy_sock+0x55/0x100
     tcp_close+0x25d/0x400
     ? tcp_check_oom+0x120/0x120
     tls_sk_proto_close+0x127/0x1c0
     inet_release+0x3c/0x60
     __sock_release+0x3d/0xb0
     sock_close+0x11/0x20
     __fput+0xd8/0x210
     task_work_run+0x84/0xa0
     do_exit+0x2dc/0xb90
     ? release_sock+0x43/0x90
     do_group_exit+0x3a/0xa0
     get_signal+0x295/0x720
     do_signal+0x36/0x610
     ? SYSC_recvfrom+0x11d/0x130
     exit_to_usermode_loop+0x69/0xb0
     do_syscall_64+0x173/0x180
     entry_SYSCALL_64_after_hwframe+0x3d/0xa2
    RIP: 0033:0x7fe9b9abc10d
    RSP: 002b:00007fe9b19a1d48 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
    RAX: fffffffffffffe00 RBX: 0000000000000006 RCX: 00007fe9b9abc10d
    RDX: 0000000000000002 RSI: 0000000000000080 RDI: 00007fe948003430
    RBP: 00007fe948003410 R08: 00007fe948003430 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000246 R12: 00005603739d9080
    R13: 00007fe9b9ab9f90 R14: 00007fe948003430 R15: 0000000000000000

Fixes: 94850257cf0f ("tls: Fix tls_device handling of partial records")
Signed-off-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
---
 include/net/tls.h  | 15 ---------------
 net/tls/tls_main.c |  3 ++-
 2 files changed, 2 insertions(+), 16 deletions(-)

diff --git a/include/net/tls.h b/include/net/tls.h
index 4a55ce6a303f..53d96bca220d 100644
--- a/include/net/tls.h
+++ b/include/net/tls.h
@@ -373,21 +373,6 @@ static inline bool tls_is_partially_sent_record(struct tls_context *ctx)
 	return !!ctx->partially_sent_record;
 }
 
-static inline int tls_complete_pending_work(struct sock *sk,
-					    struct tls_context *ctx,
-					    int flags, long *timeo)
-{
-	int rc = 0;
-
-	if (unlikely(sk->sk_write_pending))
-		rc = wait_on_pending_writer(sk, timeo);
-
-	if (!rc && tls_is_partially_sent_record(ctx))
-		rc = tls_push_partial_record(sk, ctx, flags);
-
-	return rc;
-}
-
 static inline bool tls_is_pending_open_record(struct tls_context *tls_ctx)
 {
 	return tls_ctx->pending_open_record_frags;
diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index fc81ae18cc44..e2b69e805d46 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -279,7 +279,8 @@ static void tls_sk_proto_close(struct sock *sk, long timeout)
 		goto skip_tx_cleanup;
 	}
 
-	if (!tls_complete_pending_work(sk, ctx, 0, &timeo))
+	if (unlikely(sk->sk_write_pending) &&
+	    !wait_on_pending_writer(sk, &timeo))
 		tls_handle_open_record(sk, 0);
 
 	/* We need these for tls_sw_fallback handling of other packets */
-- 
2.21.0

Re: [PATCH net] net/tls: fix page double free on TX cleanup

[David Miller]

From: Jakub Kicinski <jakub.kicinski@netronome.com>
Date: Sun, 23 Jun 2019 21:26:58 -0700

> From: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
> 
> With commit 94850257cf0f ("tls: Fix tls_device handling of partial records")
> a new path was introduced to cleanup partial records during sk_proto_close.
> This path does not handle the SW KTLS tx_list cleanup.
> 
> This is unnecessary though since the free_resources calls for both
> SW and offload paths will cleanup a partial record.
> 
> The visible effect is the following warning, but this bug also causes
> a page double free.
 ...
> Fixes: 94850257cf0f ("tls: Fix tls_device handling of partial records")
> Signed-off-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

Applied and queued up for -stable, thanks.