Date: Tue, 1 Feb 2011 13:33:49 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: cvs-src-old@freebsd.org Subject: cvs commit: src/sys/kern uipc_usrreq.c Message-ID: <201102011334.p11DY1mW002113@repoman.freebsd.org>
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kib 2011-02-01 13:33:49 UTC FreeBSD src repository Modified files: sys/kern uipc_usrreq.c Log: SVN rev 218168 on 2011-02-01 13:33:49Z by kib The unp_gc() function drops and reaquires lock between scan and collect phases. The unp_discard() function executes unp_externalize_fp(), which might make the socket eligible for gc-ing, and then, later, taskqueue will close the socket. Since unp_gc() dropped the list lock to do the malloc, close might happen after the mark step but before the collection step, causing collection to not find the socket and miss one array element. I believe that the race was there before r216158, but the stated revision made the window much wider by postponing the close to taskqueue sometimes. Only process as much array elements as we find the sockets during second phase of gc [1]. Take linkage lock and recheck the eligibility of the socket for gc, as well as call fhold() under the linkage lock. Reported and tested by: jmallett Submitted by: jmallett [1] Reviewed by: rwatson, jeff (possibly) MFC after: 1 week Revision Changes Path 1.242 +16 -12 src/sys/kern/uipc_usrreq.c
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