[Crash-utility] Module load patch for crash-4.0-3.17

Wed Jan 17 20:04:52 UTC 2007

Finding the overrun wasn't actually that hard.  It's also fixed in the
current GDB tree.

I've attached a patch which fixes the problem in symfile.c.  The point
of this patch
is to fix loading kernel modules symbol information on 2.6 for those who
have not
been following this.

Hopefully this will work on other platforms too....

   -castor

________________________________

From: crash-utility-bounces at redhat.com
[mailto:crash-utility-bounces at redhat.com] On Behalf Of Castor Fu
Sent: Wednesday, January 17, 2007 7:49 AM
To: Discussion list for crash utility usage, maintenance and
development; Discussion list for crash utility usage, maintenance and
development
Subject: RE: [Crash-utility] test results of latest 4.0-3.16.sym.patch
(ia64)

Hi Dave:

I reproduced the problem on an x86 system by creating a module with a
bunch
of sections.

I then found the following in
gdb-6.1/gdb/symfile.c:add_symbol_table_command()

    num_sec_opts = 16;

with additional code for xreallocing if it turned out to have too many
sections.

This seems to be the code which is broken.  I'm loath to figure out
exactly
what it is...  I'll put together a patch against 4.0-3.17 which jacks
this
up, and probably print a warning if we exceed the count.

Thanks for digging so far into this.

   -castor

-----Original Message-----
From: crash-utility-bounces at redhat.com on behalf of Dave Anderson
Sent: Thu 1/4/2007 8:22 AM
To: Discussion list for crash utility usage, maintenance and development
Subject: Re: [Crash-utility] test results of latest 4.0-3.16.sym.patch
(ia64)

Hi Castor,

Another FYI re: the xrealloc() crash.  The problem appears
to be specific to gdb.

I captured the "add-symbol-file" command string and saved
it in an input file.  Then I brought crash up and executed
the input file, which simply passes the suspect command line
directly to gdb, and it crashes on its own:

crash> < /tmp/junk
crash> add-symbol-file
/lib/modules/2.6.18-1.2767.el5/kernel/net/ipv6/ipv6.ko
0xa00000021ed605b0 -s .exit.text 0xa00000021edb49a0 -s .rodata
0xa00000021edbd4c8 -s __ksymtab_strings 0xa00000021edbdc08 -s __versions
0xa00000021edbdf98 -s .data 0xa00000021edd6a20 -s .data.rel.ro
0xa00000021edd6c00 -s __ksymtab_gpl 0xa00000021edd6df8 -s __kcrctab_gpl
0xa00000021edd6ed8 -s .data.rel 0xa00000021edd6f48 -s .data.rel.local
0xa00000021ee39940 -s .data.rel.ro.local 0xa00000021ee3a9c0 -s
.data.read_mostly 0xa00000021ee3a9e0 -s __ksymtab 0xa00000021ee3aa60 -s
__kcrctab 0xa00000021ee3ac30 -s .gnu.linkonce.this_module
0xa00000021ee3ad80 -s .sdata 0xa00000021ee5d730 -s .bss
0xa00000021ee5b000 -s .sbss 0xa00000021ee5e8b8
add_symbol_file_command: calling xrealloc w/argcnt: 49 arg:
[0xa00000021ee5d730]...
*** glibc detected *** ./crash: realloc(): invalid next size:
0x6000000001921fe0 ***
======= Backtrace: =========
/lib/libc.so.6.1[0x20000000002f2a70]
/lib/libc.so.6.1(realloc-0x1cb0b0)[0x20000000002f5e20]
./crash(xmrealloc+0x1fffffffffee6e20)[0x40000000003a7d00]
./crash[0x40000000002ff500]
./crash[0x40000000004221e0]
./crash(cmd_func+0x1ffffffffff61610)[0x4000000000422500]
./crash(execute_command+0x1fffffffffee25f0)[0x40000000003a34f0]
./crash(gdb_command_funnel+0x1fffffffffe2feb0)[0x40000000002f0dc0]
./crash(gdb_interface+0x1fffffffffcd7590)[0x40000000001984b0]
./crash(gdb_pass_through+0x1fffffffffcd6cb0)[0x4000000000197be0]
./crash(cmd_gdb+0x2000000000151068)[0x400000000019bbc0]
./crash(exec_command+0x1fffffffffb99db0)[0x400000000005acf0]
./crash(exec_input_file+0x1fffffffffd86d40)[0x4000000000247c90]
./crash[0x400000000005b420]
./crash(exec_command+0x1fffffffffb99e50)[0x400000000005ad90]
./crash(main_loop+0x1fffffffffb9a2e0)[0x400000000005a8e0]
./crash(current_interp_command_loop+0x200000000001fd60)[0x40000000004e0c
c0]
./crash[0x40000000003199c0]
./crash[0x400000000039f370]
./crash[0x40000000003a4260]
./crash(catch_errors+0x1fffffffffee33b0)[0x40000000003a4320]
./crash[0x400000000031a930]
./crash[0x400000000039f370]
./crash[0x40000000003a4260]
./crash(catch_errors+0x1fffffffffee33b0)[0x40000000003a4320]
./crash(gdb_main+0x1fffffffffe58960)[0x40000000003198e0]
./crash(gdb_main_entry+0x1fffffffffe589f0)[0x4000000000319980]
./crash(gdb_main_loop+0x1fffffffffcd54d0)[0x4000000000196470]
./crash(main+0x1fffffffffb99820)[0x400000000005a330]
/lib/libc.so.6.1(__libc_start_main-0x2818f0)[0x200000000023f6c0]
./crash(_start+0x1fffffffffb95240)[0x4000000000056200]
======= Memory map: ========
00000000-00004000 r--p 00000000 00:00 0
2000000000000000-2000000000038000 r-xp 00000000 fd:00 10256390
/lib/ld-2.5.so
2000000000044000-2000000000050000 rw-p 00034000 fd:00 10256390
/lib/ld-2.5.so
2000000000050000-2000000000114000 r-xp 00000000 fd:00 10256405
/lib/libm-2.5.so
2000000000114000-2000000000120000 ---p 000c4000 fd:00 10256405
/lib/libm-2.5.so
2000000000120000-2000000000124000 rw-p 000c0000 fd:00 10256405
/lib/libm-2.5.so
2000000000124000-20000000001b0000 r-xp 00000000 fd:00 10883077
/usr/lib/libncurses.so.5.5
20000000001b0000-20000000001bc000 ---p 0008c000 fd:00 10883077
/usr/lib/libncurses.so.5.5
20000000001bc000-20000000001cc000 rw-p 00088000 fd:00 10883077
/usr/lib/libncurses.so.5.5
20000000001cc000-20000000001d0000 rw-p 20000000001cc000 00:00 0
20000000001d0000-20000000001d8000 r-xp 00000000 fd:00 10256403
/lib/libdl-2.5.so
20000000001d8000-20000000001e4000 ---p 00008000 fd:00 10256403
/lib/libdl-2.5.so
20000000001e4000-20000000001e8000 rw-p 00004000 fd:00 10256403
/lib/libdl-2.5.so
20000000001e8000-200000000020c000 r-xp 00000000 fd:00 10882711
/usr/lib/libz.so.1.2.3
200000000020c000-2000000000218000 ---p 00024000 fd:00 10882711
/usr/lib/libz.so.1.2.3
2000000000218000-200000000021c000 rw-p 00020000 fd:00 10882711
/usr/lib/libz.so.1.2.3
200000000021c000-2000000000480000 r-xp 00000000 fd:00 10256397
/lib/libc-2.5.so
2000000000480000-200000000048c000 ---p 00264000 fd:00 10256397
/lib/libc-2.5.so
200000000048c000-2000000000498000 rw-p 00260000 fd:00 10256397
/lib/libc-2.5.so
2000000000498000-20000000004d8000 rw-p 2000000000498000 00:00 0
20000000004d8000-2000000003c1c000 r--p 00000000 fd:00 10882710
/usr/lib/locale/locale-archive
2000000003c1c000-2000000003c2c000 rw-p 2000000003c1c000 00:00 0
2000000003c38000-2000000003c44000 r-xp 00000000 fd:00 10256427
/lib/libthread_db-1.0.so
2000000003c44000-2000000003c50000 ---p 0000c000 fd:00 10256427
/lib/libthread_db-1.0.so
2000000003c50000-2000000003c54000 rw-p 00008000 fd:00 10256427
/lib/libthread_db-1.0.so
2000000003c54000-2000000003c58000 rw-p 2000000003c54000 00:00 0
2000000003c6c000-2000000003da0000 rw-p 2000000003c6c000 00:00 0
2000000003da0000-2000000003dbc000 r-xp 00000000 fd:00 10884674
/usr/lib/libunwind.so.7.0.0
2000000003dbc000-2000000003dc8000 ---p 0001c000 fd:00 10884674
/usr/lib/libunwind.so.7.0.0
2000000003dc8000-2000000003dcc000 rw-p 00018000 fd:00 10884674
/usr/lib/libunwind.so.7.0.0
2000000003dcc000-2000000003df0000 rw-p 2000000003dcc000 00:00 0
2000000003e00000-2000000003e08000 r--s 00000000 fd:00 10977539
/usr/lib/gconv/gconv-modules.cache
2000000003e08000-2000000003e18000 rw-p 2000000003e08000 00:00 0
2000000003e1c000-2000000006edc000 rw-p 2000000003e1c000 00:00 0
2000000006ee8000-2000000006f04000 r-xp 00000000 fd:00 10256386
/lib/libgcc_s-4.1.1-20061130.so.1
2000000006f04000-2000000006f10000 ---p 0001c000 fd:00 10256386
/lib/libgcc_s-4.1.1-20061130.so.1
2000000006f10000-2000000006f14000 rw-p 00018000 fd:00 10256386
/lib/libgcc_s-4.1.1-20061130.so.1
2000000006f14000-2000000006f24000 rw-p 2000000006f14000 00:00 0
2000000008000000-2000000008024000 rw-p 2000000008000000 00:00 0
2000000008024000-200000000c000000 ---p 2000000008024000 00:00 0
4000000000000000-40000000007e0000 r-xp 00000000 fd:00 9633909
/var/tmp/crash-4.0-3.16/crash
600000000000c000-600000000006c000 rw-p 007dc000 fd:00 9633909
/var/tmp/crash-4.0-3.16/crash
600000000006c000-6000000001fc0000 rw-p 600000000006c000 00:00 0
[heap]
60000fff7fffc000-60000fff80004000 rw-p 60000fff7fffc000 00:00 0
60000ffffe068000-60000ffffe0bc000 rw-p 60000ffffe068000 00:00 0
[stack]
a000000000000000-a000000000020000 ---p 00000000 00:00 0
[vdso]
Aborted

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