Date: Sun, 12 May 2002 22:16:35 -0700 (PDT) From: David Xu <davidx@viasoft.com.cn> To: freebsd-gnats-submit@FreeBSD.org Subject: i386/38016: i386_get_ldt range checking bug Message-ID: <200205130516.g4D5GZh8027512@www.freebsd.org>
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>Number: 38016 >Category: i386 >Synopsis: i386_get_ldt range checking bug >Confidential: no >Severity: critical >Priority: high >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Sun May 12 22:20:00 PDT 2002 >Closed-Date: >Last-Modified: >Originator: David Xu >Release: FreeBSD 5.0-CURRENT >Organization: Viatech >Environment: FreeBSD davidbsd.viasoft.com.cn 5.0-CURRENT FreeBSD 5.0-CURRENT #23: Mon May 13 12:16:30 CST 2002 davidx@davidbsd.viasoft.com.cn:/usr/src/sys/i386/compile/xu i386 >Description: function i386_get_ldt() in sys_machdep.c has range checking bug, it allow program to access LDT out of bound, may cause page fault. >How-To-Repeat: >Fix: --- /usr/src/sys/i386/i386/sys_machdep.c Wed Apr 3 02:37:41 2002 +++ /usr/src/sys/i386/i386/sys_machdep.c.new Mon May 13 11:11:19 2002 @@ -363,6 +363,7 @@ char *args; { int error = 0; + int largest_ld; struct proc_ldt *pldt = td->td_proc->p_md.md_ldt; int nldt, num; union descriptor *lp; @@ -389,7 +390,8 @@ num = min(uap->num, nldt); lp = &ldt[uap->start]; } - if (uap->start > nldt) + largest_ld = uap->start + num - 1; + if (uap->start >= nldt || largest_ld >= nldt) return(EINVAL); error = copyout(lp, uap->descs, num * sizeof(union descriptor)); >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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