From: Jakub Kicinski <jakub.kicin...@netronome.com>
[ Upstream commit 9188d5ca454fd665145904267e726e9e8d122f5c ]
Unlike atomic_add(), refcount_add() does not deal well
with a negative argument. TLS fallback code reallocates
the skb and is very likely to shrink the truesize, leading to:
[ 189.513254] WARNING: CPU: 5 PID: 0 at lib/refcount.c:81
refcount_add_not_zero_checked+0x15c/0x180
Call Trace:
refcount_add_checked+0x6/0x40
tls_enc_skb+0xb93/0x13e0 [tls]
Once wmem_allocated count saturates the application can no longer
send data on the socket. This is similar to Eric's fixes for GSO,
TCP:
commit 7ec318feeed1 ("tcp: gso: avoid refcount_t warning from
tcp_gso_segment()")
and UDP:
commit 575b65bc5bff ("udp: avoid refcount_t saturation in __udp_gso_segment()").
Unlike the GSO case, for TLS fallback it's likely that the skb has
shrunk, so the "likely" annotation is the other way around (likely
branch being "sub").
Fixes: e8f69799810c ("net/tls: Add generic NIC offload infrastructure")
Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
Reviewed-by: John Hurley <john.hur...@netronome.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
net/tls/tls_device_fallback.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
--- a/net/tls/tls_device_fallback.c
+++ b/net/tls/tls_device_fallback.c
@@ -193,6 +193,9 @@ static void update_chksum(struct sk_buff
static void complete_skb(struct sk_buff *nskb, struct sk_buff *skb, int headln)
{
+ struct sock *sk = skb->sk;
+ int delta;
+
skb_copy_header(nskb, skb);
skb_put(nskb, skb->len);
@@ -200,11 +203,15 @@ static void complete_skb(struct sk_buff
update_chksum(nskb, headln);
nskb->destructor = skb->destructor;
- nskb->sk = skb->sk;
+ nskb->sk = sk;
skb->destructor = NULL;
skb->sk = NULL;
- refcount_add(nskb->truesize - skb->truesize,
- &nskb->sk->sk_wmem_alloc);
+
+ delta = nskb->truesize - skb->truesize;
+ if (likely(delta < 0))
+ WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
+ else if (delta)
+ refcount_add(delta, &sk->sk_wmem_alloc);
}
/* This function may be called after the user socket is already
