Date: Tue, 09 May 2017 07:40:33 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 219159] sendmsg hangs (or EWOULDBLOCK) forever with ancillary data. Message-ID: <bug-219159-8@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=219159 Bug ID: 219159 Summary: sendmsg hangs (or EWOULDBLOCK) forever with ancillary data. Product: Base System Version: 10.3-STABLE Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: parakleta@darkreality.org When sending a message over a SOCK_DGRAM that has control data `sosend_generic()` in `sys/kern/uipc_socket.c` checks `if ((atomic && resid > so->so_snd.sb_hiwat) ...` to return `ESMSGSIZE` but then next checks `if (space < resid + clen && (atomic || ...` and either returns `EWOULDBLOCK` or waits in `sbwait()` and then restarts. `space` is calculated from `sbspace(&so->so_snd)` which is calculated to be the minimum of `sb_hiwat - sb_cc` and another value, and so strictly less or equal to `so->so_snd.sb_hiwat`. This means then that if it is the case that `resid <= so->so_snd.sb_hiwat` but `resid + clen > so->so_snd.sb_hiwat` the code will always pass the first test and always fail the second and so will loop forever via the `goto restart` instruction. I believe the it should be the case that `if ((atomic && resid + clen > so->so_snd.sb_hiwat) ...` the error `ESMSGSIZE` will be returned. This may be related to 181092. -- You are receiving this mail because: You are the assignee for the bug.help
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