net/tls: fix refcount adjustment in fallback
[ Upstream commit 9188d5ca ] 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 7ec318fe ("tcp: gso: avoid refcount_t warning from tcp_gso_segment()") and UDP: commit 575b65bc ("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: e8f69799 ("net/tls: Add generic NIC offload infrastructure") Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com> Reviewed-by: NJohn Hurley <john.hurley@netronome.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net> Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
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