Skip Menu |

Download (untitled) / with headers
text/plain 5.6KiB
From tlyu@MIT.EDU Wed Dec 18 02:41:56 1996
Received: from MIT.EDU (SOUTH-STATION-ANNEX.MIT.EDU []) by rt-11.MIT.EDU (8.7.5/8.7.3) with SMTP id CAA25750 for <bugs@RT-11.MIT.EDU>; Wed, 18 Dec 1996 02:41:56 -0500
Received: from TESLA-COIL.MIT.EDU by MIT.EDU with SMTP
id AA03822; Wed, 18 Dec 96 02:41:55 EST
Received: by tesla-coil.MIT.EDU (5.x/4.7) id AA03497; Wed, 18 Dec 1996 02:41:52 -0500
Message-Id: <9612180741.AA03497@tesla-coil.MIT.EDU>
Date: Wed, 18 Dec 1996 02:41:52 -0500
From: tlyu@MIT.EDU
Reply-To: tlyu@MIT.EDU
To: krb5-bugs@MIT.EDU
Subject: gssrpc coredumps in recvmsg() [post-1.0]
X-Send-Pr-Version: 3.99

Show quoted text
>Number: 301
>Category: krb5-libs
>Synopsis: gssrpc coredumps in recvmsg()
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: bjaspan
>State: closed
>Class: sw-bug
>Submitter-Id: unknown
>Arrival-Date: Wed Dec 18 02:42:01 EST 1996
>Last-Modified: Sun Feb 22 21:21:51 EST 1998
>Originator: Tom Yu
Show quoted text
>Release: post-1.0

System: SunOS tesla-coil 5.4 Generic_101945-37 sun4m sparc

Show quoted text
I found this on the mainline; don't panic...
Basically the rpc unit tests fail due to a coredump deep in the rpc

Core was generated by `./server -u'.
Program terminated with signal 11, Segmentation fault.

[spewage deleted]

#0 0xef5aa710 in recvmsg ()
(gdb) bt
#0 0xef5aa710 in recvmsg ()
#1 0xef791ad0 in svcudp_recv (xprt=0x220f8, msg=0xefffe980)
at ../../../src/lib/rpc/svc_udp.c:188
#2 0xef78d688 in svc_getreqset (readfds=0xefffea28)
at ../../../src/lib/rpc/svc.c:430
#3 0xef7906e8 in svc_run () at ../../../src/lib/rpc/svc_run.c:69
#4 0x11244 in main (argc=0, argv=0xefffebac)
at ../../../../src/lib/rpc/unit-test/server.c:120
(gdb) up
#1 0xef791ad0 in svcudp_recv (xprt=0x220f8, msg=0xefffe980)
at ../../../src/lib/rpc/svc_udp.c:188
188 rlen = recvmsg(xprt->xp_sock, &dummy, MSG_PEEK);
(gdb) info locals
dummy = {msg_name = 0x221", msg_namelen = 16, msg_iov = 0x0,
msg_iovlen = 0, msg_accrights = 0x0, msg_accrightslen = 0}
su = (struct svcudp_data *) 0x22150
xdrs = (XDR *) 0x22158
rlen = 0
reply = 0x0
replylen = 0

diassembling a bit...

0xef5aa66c <recvmsg>: save %sp, -184, %sp
0xef5aa670 <recvmsg+4>: st %i2, [ %fp + 0x4c ]
0xef5aa674 <recvmsg+8>: mov 0xc, %l3
0xef5aa678 <recvmsg+12>: ld [ %i1 + 0xc ], %o0
0xef5aa67c <recvmsg+16>: cmp %o0, 1
0xef5aa680 <recvmsg+20>: ble,a 0xef5aa70c <recvmsg+160>
0xef5aa684 <recvmsg+24>: ld [ %i1 + 8 ], %i3
0xef5aa688 <recvmsg+28>: clr %i4
0xef5aa708 <recvmsg+156>: nop
0xef5aa70c <recvmsg+160>: ld [ %i1 + 8 ], %l5
0xef5aa710 <recvmsg+164>: ld [ %i3 + 4 ], %i3
0xef5aa714 <recvmsg+168>: ld [ %l5 ], %l5
0xef5aa718 <recvmsg+172>: call 0xef5bcda0 <.L670+67820>

[disclaimer... I'm not that clueful about sparc assembler...]

Here I'm assuming %i0 gets the first arg, %i1 gets the second, etc.,
thus %i1 + 0xc is &msg->msg_iovlen, and %o0 gets msg->msg_iovlen == 0.
I'm guessing that there are one or two jump slots after the ble
instruction, so that %i3 gets msg->msg_iov, which is NULL. This makes
sense that the fault would occur on the "ld [ %i3 + 4 ], %i3".

(gdb) p $i0
$19 = 4
(gdb) p (char*)$i1
$21 = 0xefffe3f8 ""
(gdb) p $i2
$22 = 2
(gdb) p $i3
$23 = 0
(gdb) up
#1 0xef791ad0 in svcudp_recv (xprt=0x220f8, msg=0xefffe980)
at ../../../src/lib/rpc/svc_udp.c:188
188 rlen = recvmsg(xprt->xp_sock, &dummy, MSG_PEEK);
(gdb) p &dummy
$14 = (struct msghdr *) 0xefffe3f8
(gdb) p xprt->xp_sock
$24 = 4

Anyway, it does seem to point rather strongly in favor of the
conclusion that recvmsg() doesn't check to see if msg->msg_iov is a
NULL pointer, or if msg->msg_iovlen is zero.

Show quoted text
Try running make check in lib/rpc.
Show quoted text
* Pester Sun about recvmsg() being broken. (yeah, right) It
is not clear that they're at fault; the manpage doesn't say what
recvmsg() does if it gets a NULL msg->msg_iovec.

* Fix svcudp_recv() so that it actually passes an iovec.
Show quoted text

Responsible-Changed-From-To: krb5-unassigned->bjaspan
Responsible-Changed-By: tlyu
Responsible-Changed-When: Wed Dec 18 02:45:24 1996

I think Barry is the one to make the change that caused this

From: "Barry Jaspan" <bjaspan@MIT.EDU>
To: tlyu@MIT.EDU
Cc: krb5-bugs@MIT.EDU
Subject: Re: krb5-libs/301: gssrpc coredumps in recvmsg()
Date: Wed, 18 Dec 1996 11:57:43 -0500

This feels a lot like a bug in recvmsg(). However, it is easy enough
for the code to call recvmsg with a non-zero iovec and ignore the
results (it is passed the MSG_PEEK flag anyway).

State-Changed-From-To: open-analyzed
State-Changed-By: tlyu
State-Changed-When: Tue Feb 11 11:45:42 1997

I have a partial fix; udp transport gssrpc now only fails without
coredumping on Solaris. I've patched svc_udp.c to use a non-NULL
iovec to avoid the coredump, but there are still problems because
Solaris is broken and returns INADDR_ANY on a connected udp socket
that was originally bound to INADDR_ANY, unlike almost every other
sane socket implementation. This results in the bad channel bindings
error. I don't know whether this is fixed in Solaris 2.5, but if it
isn't, we may want to mark the udp test case as an expected failure.

Incidentally, this is probably the second bug I've found in Solaris
udp socket code.

changed files: svc_udp.c 1.13, 1.14 (ezra's patch to explicitly
include uio.h)

State-Changed-From-To: analyzed-closed
State-Changed-By: tlyu
State-Changed-When: Sun Feb 22 21:21:14 1998

Don't run the UDP gssrpc tests under Solaris 2.[12345]*

Show quoted text