Re: Reported regression against commit a05d2ad

Herton Ronaldo Krzesinski [off-list ref] writes:

Hi,

after update to one of the latest 2.6.32.x stable kernels for Ubuntu, we
got a regression report about timeout in tcp connections
(https://launchpad.net/bugs/791512).

We tried help reporter with a bisect process, but it was taking some
time, so we reverted some suspect commits, until we isolated it to
commit "af_unix: Only allow recv on connected seqpacket sockets."

With only commit a05d2ad reverted, testing results so far indicate the
issue doesn't happen.

I'm unfamiliar with unix sockets code, so can't see at first why this
commit in particular is causing problems, for now I can only say may be
something at application level using unix sockets regressed with it (?).
I'm just reporting it right now, and we plan to revert it for that kernel
until more info is found about it.

The only thing commit a05d2ad will prevent is a non-sense use of a
af_unix socket, and on recent enough kernels a NULL pointer deference.

I respectfully suggest that the bug is elsewhere perhaps a broken user
space application out there that needs to be fixed, or you have a kernel
memory stomp that removing patch a05d2ad happens to shift the memory
layout to be harmful in a different way.

af_unix sockets have nothing to do with tcp and only happen to use
the TCP_ESTABLISHED flag to indicated connected or non-connected
sockets.

Eric

I'm adding reporter to CC (Lamont), in case more details are necessary
etc.