Date: Fri, 16 Mar 2001 20:23:51 -0800 From: Dima Dorfman <dima@unixfreak.org> To: hackers@freebsd.org Subject: sysctl_kern_proc doesn't handle the case when no procs match given criteria Message-ID: <20010317042351.C1B283E23@bazooka.unixfreak.org>
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Hello -hackers
The sysctl_kern_proc routine in kern_proc.c doesn't handle the case
when no processes match the given criteria. I.e., if no processes
match, it will return 0 even though it never called SYSCTL_OUT; thus,
the output data is junk. This can be demonstrated by giving ps(1)
arguments such that no processes match. In this example, the user
`nobody' isn't running anything:
dd@ref5% ps U nobody
ps: kinfo_proc size mismatch (expected 648, got -791621424)
Obviously, this isn't the desired mode of failure. Attached is a
patch that will make sysctl_kern_proc return ESRCH if it didn't find
any processes. AFAIK, without the patch, the only way to detect this
condition (no processes match search criteria) is to check that a call
into this routine via sysctl didn't modify whatever is pointed at by
the oldp pointer (see sysctl(3)).
Comments? Suggestions?
Thanks
Dima Dorfman
dima@unixfreak.org
P.S. libkvm and/or ps(1) should probably be taught to check for this
condition and react more gently (on -stable, ps just prints the column
labels when this happens). I'll probably do this later.
Index: kern_proc.c
===================================================================
RCS file: /st/src/FreeBSD/src/sys/kern/kern_proc.c,v
retrieving revision 1.89
diff -u -r1.89 kern_proc.c
--- kern_proc.c 2001/03/07 06:52:12 1.89
+++ kern_proc.c 2001/03/17 04:20:49
@@ -555,6 +555,7 @@
struct proc *p;
int doingzomb;
int error = 0;
+ int match = 0;
if (oidp->oid_number == KERN_PROC_PID) {
if (namelen != 1)
@@ -640,9 +641,12 @@
ALLPROC_LOCK(AP_RELEASE);
return (error);
}
+ match = 1;
}
}
ALLPROC_LOCK(AP_RELEASE);
+ if (!match)
+ return (ESRCH);
return (0);
}
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