Date: Tue, 20 Nov 2007 16:22:53 GMT From: Ivan Shcheklein <shcheklein@gmail.com> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/118153: [fix] "semprt" can be invalid after wakeup in the semop() Message-ID: <200711201622.lAKGMr7e098210@www.freebsd.org> Resent-Message-ID: <200711201630.lAKGU1t6030754@freefall.freebsd.org>
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>Number: 118153 >Category: kern >Synopsis: [fix] "semprt" can be invalid after wakeup in the semop() >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Tue Nov 20 16:30:01 UTC 2007 >Closed-Date: >Last-Modified: >Originator: Ivan Shcheklein >Release: FREEBSD-6.2 >Organization: ISP RAS >Environment: FreeBSD 6.2-RELEASE i386 >Description: Fistly, sorry for the my previous post of this bug: http://lists.freebsd.org/pipermail/freebsd-bugs/2007-November/026847.html I didn't know about the better way to submit bugs. I think, it can be removed or marked as duplicate to this one. The buf itself is the following. In sysv_sem.c::1173 we have: /* ... semaphores wakes up ... */ if (sopptr->sem_op == 0) semptr->semzcnt--; else semptr->semncnt--; Used here "semptr" after wakeup can be invalid due to "semakptr->u.sem_base" can be changed during semaphore sleeping. (For example it can be changed by removing another semaphore). >How-To-Repeat: >Fix: The solution for this problem is quiet obvious. We must use "semakptr" to get new "semptr". For example (possibly it can be written better): if (sopptr->sem_op == 0) (&semakptr->u.sem_base[sopptr->sem_num])->semzcnt--; else (&semakptr->u.sem_base[sopptr->sem_num])->semncnt--; >Release-Note: >Audit-Trail: >Unformatted:
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