tls: adjust recv return with async crypto and failed copy to userspace

[ Upstream commit 85eef9a41d019b59be7bc91793f26251909c0710 ]

process_rx_list may not copy as many bytes as we want to the userspace
buffer, for example in case we hit an EFAULT during the copy. If this
happens, we should only count the bytes that were actually copied,
which may be 0.

Subtracting async_copy_bytes is correct in both peek and !peek cases,
because decrypted == async_copy_bytes + peeked for the peek case: peek
is always !ZC, and we can go through either the sync or async path. In
the async case, we add chunk to both decrypted and
async_copy_bytes. In the sync case, we add chunk to both decrypted and
peeked. I missed that in commit 6caaf104423d ("tls: fix peeking with
sync+async decryption").

Fixes: 4d42cd6bc2ac ("tls: rx: fix return value for async crypto")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/1b5a1eaab3c088a9dd5d9f1059ceecd7afe888d1.1711120964.git.sd@queasysnail.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 8e753d10e694a635db8c41e8176f0eb52cc6a6fd..925de4caa894a19f46a557a9b59207a4535a1e09 100644 (file)
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -2158,6 +2158,9 @@ recv_end:
                else
                        err = process_rx_list(ctx, msg, &control, 0,
                                              async_copy_bytes, is_peek, NULL);
+
+               /* we could have copied less than we wanted, and possibly nothing */
+               decrypted += max(err, 0) - async_copy_bytes;
        }
 
        copied += decrypted;