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authorJakub Kicinski <jakub.kicinski@netronome.com>2019-04-17 19:51:19 +0200
committerDavid S. Miller <davem@davemloft.net>2019-04-19 01:51:03 +0200
commit9188d5ca454fd665145904267e726e9e8d122f5c (patch)
tree5ae8e056f8215559af87108a39e46d203876ac0e /net/tls
parentstmmac: pci: Adjust IOT2000 matching (diff)
downloadlinux-9188d5ca454fd665145904267e726e9e8d122f5c.tar.xz
linux-9188d5ca454fd665145904267e726e9e8d122f5c.zip
net/tls: fix refcount adjustment in fallback
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.kicinski@netronome.com> Reviewed-by: John Hurley <john.hurley@netronome.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tls')
-rw-r--r--net/tls/tls_device_fallback.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/net/tls/tls_device_fallback.c b/net/tls/tls_device_fallback.c
index 54c3a758f2a7..a3ebd4b02714 100644
--- a/net/tls/tls_device_fallback.c
+++ b/net/tls/tls_device_fallback.c
@@ -194,6 +194,9 @@ static void update_chksum(struct sk_buff *skb, int headln)
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);
@@ -201,11 +204,15 @@ static void complete_skb(struct sk_buff *nskb, struct sk_buff *skb, int headln)
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