* [PATCH mptcp-net] mptcp: fix sk_forward_memory corruption under memory pressure
@ 2021-05-14 10:05 Paolo Abeni
2021-05-14 21:44 ` Mat Martineau
2021-05-17 19:15 ` Matthieu Baerts
0 siblings, 2 replies; 3+ messages in thread
From: Paolo Abeni @ 2021-05-14 10:05 UTC (permalink / raw)
To: MPTCP Upstream
MPTCP sk_forward_memory handling is a bit special, as such field
is protected by the msk socket spin_lock, instead of the plain
socket lock.
Currently we have a code path updating such field without handling
the relevant lock:
__mptcp_retrans() -> __mptcp_clean_una_wakeup() -> __mptcp_update_wmem()
We can hit the above only under memory pressure. When that happen,
forward memory accounting could be corrupted, as reported by Mat.
Address the issue creating a new variant of __mptcp_clean_una_wakeup()
which handle fwd memory updates with the proper care and invoking
such new helper in the relevant code path.
Reported-by: 'Matthieu Baerts <matthieu.baerts@tessares.net>'
Fixes: 64b9cea7a0af ("mptcp: fix spurious retransmissions")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
net/mptcp/protocol.c | 36 ++++++++++++++++++++++++++++--------
1 file changed, 28 insertions(+), 8 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 2d21a4793d9d..1d5d451e9211 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -947,6 +947,10 @@ static void __mptcp_update_wmem(struct sock *sk)
{
struct mptcp_sock *msk = mptcp_sk(sk);
+#ifdef CONFIG_LOCKDEP
+ WARN_ON_ONCE(!lockdep_is_held(&sk->sk_lock.slock));
+#endif
+
if (!msk->wmem_reserved)
return;
@@ -1027,7 +1031,7 @@ static void dfrag_clear(struct sock *sk, struct mptcp_data_frag *dfrag)
put_page(dfrag->page);
}
-static void __mptcp_clean_una(struct sock *sk)
+static bool __mptcp_do_clean_una(struct sock *sk)
{
struct mptcp_sock *msk = mptcp_sk(sk);
struct mptcp_data_frag *dtmp, *dfrag;
@@ -1068,12 +1072,6 @@ static void __mptcp_clean_una(struct sock *sk)
}
out:
- if (cleaned) {
- if (tcp_under_memory_pressure(sk)) {
- __mptcp_update_wmem(sk);
- sk_mem_reclaim_partial(sk);
- }
- }
if (snd_una == READ_ONCE(msk->snd_nxt)) {
if (msk->timer_ival && !mptcp_data_fin_enabled(msk))
@@ -1081,6 +1079,15 @@ static void __mptcp_clean_una(struct sock *sk)
} else {
mptcp_reset_timer(sk);
}
+ return cleaned;
+}
+
+static void __mptcp_clean_una(struct sock *sk)
+{
+ if (__mptcp_do_clean_una(sk) && tcp_under_memory_pressure(sk)) {
+ __mptcp_update_wmem(sk);
+ sk_mem_reclaim_partial(sk);
+ }
}
static void __mptcp_clean_una_wakeup(struct sock *sk)
@@ -1089,6 +1096,19 @@ static void __mptcp_clean_una_wakeup(struct sock *sk)
mptcp_write_space(sk);
}
+/* variant __mptcp_clean_una_wakeup() for caller owning the msk socket lock,
+ * but not the msk_data_lock/msk socket spin lock
+ */
+static void mptcp_clean_una_wakeup(struct sock *sk)
+{
+#ifdef CONFIG_LOCKDEP
+ WARN_ON_ONCE(!lockdep_is_held(&sk->sk_lock));
+#endif
+ if (__mptcp_do_clean_una(sk) && tcp_under_memory_pressure(sk))
+ mptcp_mem_reclaim_partial(sk);
+ mptcp_write_space(sk);
+}
+
static void mptcp_enter_memory_pressure(struct sock *sk)
{
struct mptcp_subflow_context *subflow;
@@ -2299,7 +2319,7 @@ static void __mptcp_retrans(struct sock *sk)
struct sock *ssk;
int ret;
- __mptcp_clean_una_wakeup(sk);
+ mptcp_clean_una_wakeup(sk);
dfrag = mptcp_rtx_head(sk);
if (!dfrag) {
if (mptcp_data_fin_enabled(msk)) {
--
2.26.3
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH mptcp-net] mptcp: fix sk_forward_memory corruption under memory pressure
2021-05-14 10:05 [PATCH mptcp-net] mptcp: fix sk_forward_memory corruption under memory pressure Paolo Abeni
@ 2021-05-14 21:44 ` Mat Martineau
2021-05-17 19:15 ` Matthieu Baerts
1 sibling, 0 replies; 3+ messages in thread
From: Mat Martineau @ 2021-05-14 21:44 UTC (permalink / raw)
To: Paolo Abeni; +Cc: MPTCP Upstream
On Fri, 14 May 2021, Paolo Abeni wrote:
> MPTCP sk_forward_memory handling is a bit special, as such field
> is protected by the msk socket spin_lock, instead of the plain
> socket lock.
>
> Currently we have a code path updating such field without handling
> the relevant lock:
>
> __mptcp_retrans() -> __mptcp_clean_una_wakeup() -> __mptcp_update_wmem()
>
> We can hit the above only under memory pressure. When that happen,
> forward memory accounting could be corrupted, as reported by Mat.
>
Me? :)
> Address the issue creating a new variant of __mptcp_clean_una_wakeup()
> which handle fwd memory updates with the proper care and invoking
> such new helper in the relevant code path.
>
> Reported-by: 'Matthieu Baerts <matthieu.baerts@tessares.net>'
> Fixes: 64b9cea7a0af ("mptcp: fix spurious retransmissions")
and
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/172
correct?
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> ---
> net/mptcp/protocol.c | 36 ++++++++++++++++++++++++++++--------
> 1 file changed, 28 insertions(+), 8 deletions(-)
>
> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> index 2d21a4793d9d..1d5d451e9211 100644
> --- a/net/mptcp/protocol.c
> +++ b/net/mptcp/protocol.c
> @@ -947,6 +947,10 @@ static void __mptcp_update_wmem(struct sock *sk)
> {
> struct mptcp_sock *msk = mptcp_sk(sk);
>
> +#ifdef CONFIG_LOCKDEP
> + WARN_ON_ONCE(!lockdep_is_held(&sk->sk_lock.slock));
> +#endif
> +
> if (!msk->wmem_reserved)
> return;
>
> @@ -1027,7 +1031,7 @@ static void dfrag_clear(struct sock *sk, struct mptcp_data_frag *dfrag)
> put_page(dfrag->page);
> }
>
> -static void __mptcp_clean_una(struct sock *sk)
> +static bool __mptcp_do_clean_una(struct sock *sk)
> {
> struct mptcp_sock *msk = mptcp_sk(sk);
> struct mptcp_data_frag *dtmp, *dfrag;
> @@ -1068,12 +1072,6 @@ static void __mptcp_clean_una(struct sock *sk)
> }
>
> out:
> - if (cleaned) {
> - if (tcp_under_memory_pressure(sk)) {
> - __mptcp_update_wmem(sk);
> - sk_mem_reclaim_partial(sk);
> - }
> - }
>
> if (snd_una == READ_ONCE(msk->snd_nxt)) {
> if (msk->timer_ival && !mptcp_data_fin_enabled(msk))
> @@ -1081,6 +1079,15 @@ static void __mptcp_clean_una(struct sock *sk)
> } else {
> mptcp_reset_timer(sk);
> }
> + return cleaned;
> +}
> +
> +static void __mptcp_clean_una(struct sock *sk)
> +{
> + if (__mptcp_do_clean_una(sk) && tcp_under_memory_pressure(sk)) {
> + __mptcp_update_wmem(sk);
> + sk_mem_reclaim_partial(sk);
> + }
> }
>
> static void __mptcp_clean_una_wakeup(struct sock *sk)
> @@ -1089,6 +1096,19 @@ static void __mptcp_clean_una_wakeup(struct sock *sk)
> mptcp_write_space(sk);
> }
>
> +/* variant __mptcp_clean_una_wakeup() for caller owning the msk socket lock,
> + * but not the msk_data_lock/msk socket spin lock
> + */
> +static void mptcp_clean_una_wakeup(struct sock *sk)
> +{
> +#ifdef CONFIG_LOCKDEP
> + WARN_ON_ONCE(!lockdep_is_held(&sk->sk_lock));
> +#endif
> + if (__mptcp_do_clean_una(sk) && tcp_under_memory_pressure(sk))
> + mptcp_mem_reclaim_partial(sk);
> + mptcp_write_space(sk);
> +}
> +
> static void mptcp_enter_memory_pressure(struct sock *sk)
> {
> struct mptcp_subflow_context *subflow;
> @@ -2299,7 +2319,7 @@ static void __mptcp_retrans(struct sock *sk)
> struct sock *ssk;
> int ret;
>
> - __mptcp_clean_una_wakeup(sk);
> + mptcp_clean_una_wakeup(sk);
> dfrag = mptcp_rtx_head(sk);
> if (!dfrag) {
> if (mptcp_data_fin_enabled(msk)) {
> --
> 2.26.3
Looks good to me. Thanks Paolo.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
--
Mat Martineau
Intel
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH mptcp-net] mptcp: fix sk_forward_memory corruption under memory pressure
2021-05-14 10:05 [PATCH mptcp-net] mptcp: fix sk_forward_memory corruption under memory pressure Paolo Abeni
2021-05-14 21:44 ` Mat Martineau
@ 2021-05-17 19:15 ` Matthieu Baerts
1 sibling, 0 replies; 3+ messages in thread
From: Matthieu Baerts @ 2021-05-17 19:15 UTC (permalink / raw)
To: Paolo Abeni, Mat Martineau; +Cc: MPTCP Upstream
Hi Paolo, Mat,
On 14/05/2021 12:05, Paolo Abeni wrote:
> MPTCP sk_forward_memory handling is a bit special, as such field
> is protected by the msk socket spin_lock, instead of the plain
> socket lock.
>
> Currently we have a code path updating such field without handling
> the relevant lock:
>
> __mptcp_retrans() -> __mptcp_clean_una_wakeup() -> __mptcp_update_wmem()
>
> We can hit the above only under memory pressure. When that happen,
> forward memory accounting could be corrupted, as reported by Mat.
>
> Address the issue creating a new variant of __mptcp_clean_una_wakeup()
> which handle fwd memory updates with the proper care and invoking
> such new helper in the relevant code path.
>
> Reported-by: 'Matthieu Baerts <matthieu.baerts@tessares.net>'
> Fixes: 64b9cea7a0af ("mptcp: fix spurious retransmissions")
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Thank you for the patch and the review!
Now in our tree with Mat's RvB tag, a small checkpatch fix, my Tested-by
tag, s/Mat/Matt/ and the Closes tag.
- e31f8077084d: mptcp: fix sk_forward_memory corruption under memory
pressure
- Results: 36a7db06660a..6273c44bc200
Builds and tests are now in progress:
https://cirrus-ci.com/github/multipath-tcp/mptcp_net-next/export/20210517T191245
https://github.com/multipath-tcp/mptcp_net-next/actions/workflows/build-validation.yml?query=branch:export/20210517T191245
Cheers,
Matt
--
Tessares | Belgium | Hybrid Access Solutions
www.tessares.net
^ permalink raw reply [flat|nested] 3+ messages in thread
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