Date: Thu, 6 Mar 1997 04:49:17 +0100 (MET) From: Tor Egge <Tor.Egge@idt.ntnu.no> To: FreeBSD-gnats-submit@freebsd.org Subject: kern/2891: cdstart are sometimes called at too low spl level Message-ID: <199703060349.EAA00846@ikke.idt.unit.no> Resent-Message-ID: <199703060350.TAA08205@freefall.freebsd.org>
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>Number: 2891
>Category: kern
>Synopsis: cdstart are sometimes called at too low spl level
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Mar 5 19:50:01 PST 1997
>Last-Modified:
>Originator: Tor Egge
>Organization:
Norwegian University of Science and Technology, Trondheim, Norway
>Release: FreeBSD 3.0-CURRENT i386
>Environment:
FreeBSD ikke.idt.unit.no 3.0-CURRENT FreeBSD 3.0-CURRENT #3: Thu Mar 6 02:18:52 MET 1997 root@ikke.idt.unit.no:/usr/src/sys/compile/TEGGE i386
>Description:
scsi_scsi_cmd calls free_xs without first calling splbio().
free_xs then proceeds to call start routines as, e.g., cdstart.
Many routines that call scsi_scsi_cmd do not call splbio() before calling
scsi_scsi_cmd.
By performing the ioctl function CDIOREADTOCHEADER, the call stack at
one point is
cdioctl
scsi_ioctl
cd_ioctl
cd_read_toc
scsi_scsi_cmd
free_xs
cdstart
with a too low spl level.
>How-To-Repeat:
Perform an ioctl function that calls scsi_scsi_cmd without first calling
splbio(), e.g. CDIOREADTOCHEADER.
>Fix:
This patch encloses the call to free_xs from scsi_scsi_cmd inside
a splbio()/splx() pair.
Index: scsi_base.c
===================================================================
RCS file: /home/ncvs/src/sys/scsi/scsi_base.c,v
retrieving revision 1.43
diff -c -6 -r1.43 scsi_base.c
*** scsi_base.c 1997/01/30 22:47:55 1.43
--- scsi_base.c 1997/03/06 01:18:32
***************
*** 612,624 ****
--- 612,627 ----
}
/*
* we have finished with the xfer stuct, free it and
* check if anyone else needs to be started up.
*/
bad:
+ /* Need splbio since free_xs might call cdstart */
+ s = splbio();
free_xs(xs, sc_link, flags); /* includes the 'start' op */
+ splx(s);
if (bp && retval) {
bp->b_error = retval;
bp->b_flags |= B_ERROR;
biodone(bp);
}
return (retval);
>Audit-Trail:
>Unformatted:
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