John Fastabend says:
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tls fixes for SPLICE with more hint
Syzbot found a splat where it tried to splice data over a tls socket
with the more hint and sending greater than the number of frags that
fit in a msg scatterlist. This resulted in an error where we do not
correctly send the data when the msg sg is full. The more flag being
just a hint not a strict contract. This then results in the syzbot
warning on the next send.
Edward generated an initial patch for this which checked for a full
msg on entry to the sendmsg hook. This fixed the WARNING, but didn't
fully resolve the issue because the full msg_pl scatterlist was never
sent resulting in a stuck socket. In this series instead avoid the
situation by forcing the send on the splice that fills the scatterlist.
Also in original thread I mentioned it didn't seem to be enough to
simply fix the send on full sg problem. That was incorrect and was
really a bug in my test program that was hanging the test program.
I had setup a repair socket and wasn't handling it correctly so my
tester got stuck.
Thanks. Please review. Fix in patch 1 and test in patch 2.
v2: use SPLICE_F_ flag names instead of cryptic 0xe
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Signed-off-by: David S. Miller <davem@davemloft.net>