mdadm-2.2 SEGFAULT: mdadm --assemble --scan

sorry if this is already known/fixed: Assemble() is called from mdadm.c with
the "update" argument equal to NULL:

	Assemble(ss, array_list->devname, mdfd, array_list, configfile,
		NULL, readonly, runstop, NULL, verbose-quiet, force);

But in Assemble.c we have

	if (ident->uuid_set && (!update && strcmp(update, "uuid")!= 0) && ...

which yields a segfault in glibc's strcmp().

Andre
-- 
Jesus not only saves, he also frequently makes backups

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Hi!

Andre Noll schrieb:

sorry if this is already known/fixed: Assemble() is called from mdadm.c with
the "update" argument equal to NULL:

	Assemble(ss, array_list->devname, mdfd, array_list, configfile,
		NULL, readonly, runstop, NULL, verbose-quiet, force);

But in Assemble.c we have

	if (ident->uuid_set && (!update && strcmp(update, "uuid")!= 0) && ...

which yields a segfault in glibc's strcmp().

I just found the same problem after upgrading to mdadm-2.2
The logic to test for update not being NULL seems to be
reversed.

I created a small patch which seems to cure the problem
(see attached file)

HTH

- - andreas

- --
Andreas Haumer                     | mailto:andreas@xss.co.at
*x Software + Systeme              | http://www.xss.co.at/
Karmarschgasse 51/2/20             | Tel: +43-1-6060114-0
A-1100 Vienna, Austria             | Fax: +43-1-6060114-71
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Andreas Haumer wrote:

Is that right now? Because && evaluates to zero or one left to right, 
the parens and the "!=0" are not needed, and I assume they're in for a 
reason (other than to make the code hard to understand). A comment 
before that if would make the intention clear, I originally though the 
"(!update" was intended to be "!(update" which would explain the parens, 
but that seems wrong.

If it actually works as intended with the patch, perhaps a comment and 
cleanup in 2.3?

-- 
bill davidsen [off-list ref]
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979

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Hi!

Bill Davidsen schrieb:

Andreas Haumer wrote:

- ------------------------------------------------------------------------

quoted

Index: mdadm/Assemble.c
===================================================================
RCS file: /home/cvs/repository/distribution/Utilities/mdadm/Assemble.c,v
retrieving revision 1.1.1.7
diff -u -r1.1.1.7 Assemble.c
- --- mdadm/Assemble.c    5 Dec 2005 05:56:20 -0000    1.1.1.7

+++ mdadm/Assemble.c    31 Dec 2005 15:01:34 -0000

@@ -219,7 +219,7 @@
        }
        if (dfd >= 0) close(dfd);

quoted

- -        if (ident->uuid_set && (!update && strcmp(update, "uuid")!=
0) &&
+        if (ident->uuid_set && (update && strcmp(update, "uuid")!= 0) &&
            (!super || same_uuid(info.uuid, ident->uuid,
tst->ss->swapuuid)==0)) {
            if ((inargv && verbose >= 0) || verbose > 0)
                fprintf(stderr, Name ": %s has wrong uuid.\n",

quoted

Is that right now? Because && evaluates to zero or one left to right,
the parens and the "!=0" are not needed, and I assume they're in for a
reason (other than to make the code hard to understand). A comment
before that if would make the intention clear, I originally though the
"(!update" was intended to be "!(update" which would explain the parens,
but that seems wrong.

I made this modification out of the following reasoning:

It does not make sense to check if update is NULL and
then use it in a strcmp(). It only makes sense to check
if update is _not_ NULL and then do the strcmp()

(a similar code fragment can be found in the same sourcefile
several lines below)

This cures the segfault, but I can not really say if the
whole construct is logically correct (you are right, it
looks suspicious...)
That should be answered by Neil ;-)

- - andreas

- --
Andreas Haumer                     | mailto:andreas@xss.co.at
*x Software + Systeme              | http://www.xss.co.at/
Karmarschgasse 51/2/20             | Tel: +43-1-6060114-0
A-1100 Vienna, Austria             | Fax: +43-1-6060114-71
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