depmod (kmod 21 and older) fails for allmodconfig on ARM

depmod (kmod 21 and older) fails for allmodconfig on ARM

[Alexander Holler]

Hello,

make allmodconfig
make -j4 zImage modules && make modules_install

fails here on an ARM system with a malloc bug in depmod (after finding 
some circles).

It seems to happen with older versions of kmod too, but I haven't found 
the time to search the problem (gdb doesn't help much and my glibc 
doesn't have debug symbols, so valgrind doesn't work).

Maybe someone here likes to go hunting.

Regards,

Alexander Holler

Re: depmod (kmod 21 and older) fails for allmodconfig on ARM

[Lucas De Marchi]

On Wed, Sep 23, 2015 at 7:45 AM, Alexander Holler <holler@ahsoftware.de> wrote:
> Hello,
>
> make allmodconfig
> make -j4 zImage modules && make modules_install
>
> fails here on an ARM system with a malloc bug in depmod (after finding some
> circles).

The bug in kmod should be fixed indeed, but if you have dep cycles you
have other things to fix too.  What tree are you building? Do you have
any changes on top? malloc bug... looks like corrupted memory, but
very difficult to debug any further without more info.


Lucas De Marchi

Re: depmod (kmod 21 and older) fails for allmodconfig on ARM

[Alexander Holler]

Am 24.09.2015 um 03:24 schrieb Lucas De Marchi:
> On Wed, Sep 23, 2015 at 7:45 AM, Alexander Holler <holler@ahsoftware.de> wrote:
>> Hello,
>>
>> make allmodconfig
>> make -j4 zImage modules && make modules_install
>>
>> fails here on an ARM system with a malloc bug in depmod (after finding some
>> circles).
>
> The bug in kmod should be fixed indeed, but if you have dep cycles you
> have other things to fix too.  What tree are you building? Do you have

Currently I don't intend to fix these cycles. Sorry, but I'm unable to 
fix the world and instead I try to fix stuff (including writing bug 
reports) according to my very limited resources. Maybe I will try to 
debug kmod/depmod with some memory checkers, but I thought it makes 
sense to ask people with more knowledge about depmod before wasting time.

> any changes on top? malloc bug... looks like corrupted memory, but
> very difficult to debug any further without more info.

I've used it on 4.2.1. It fails on an ARM box as well as on a x86_64 
Fedora 21 system using a cross-compiler.

Here are the steps to reproduce on a x86 system:

cp -ar linux.git /tmp
cd /tmp/linux.git
make clean
git checkout -b depmod_bug v4.2.1
ARCH=arm CROSS_COMPILE=arm-linux-gnu- make multi_v7_defconfig
ARCH=arm CROSS_COMPILE=arm-linux-gnu- make allmodconfig
# the following two steps will need quiet some time
ARCH=arm CROSS_COMPILE=arm-linux-gnu- make -j4 zImage modules
ARCH=arm INSTALL_MOD_PATH=/tmp CROSS_COMPILE=arm-linux-gnu- make -j4 
modules_install
(...)
   DEPMOD  4.2.1
depmod: ERROR: Found 10 modules in dependency cycles!
depmod: ERROR: Cycle detected: drm_kms_helper -> syscopyarea
*** Error in `/sbin/depmod': free(): invalid next size (fast): 
0x0000000003e0c370 ***
======= Backtrace: =========
/lib64/libc.so.6(+0x77d9e)[0x7f3ec21c1d9e]
/lib64/libc.so.6(cfree+0x5b5)[0x7f3ec21cd9f5]
/sbin/depmod[0x409805]
/lib64/libc.so.6(__libc_start_main+0xf0)[0x7f3ec2169fe0]
/sbin/depmod[0x40262c]
======= Memory map: ========
00400000-00423000 r-xp 00000000 00:0f 1633727 
  /usr/bin/kmod
00622000-00623000 r--p 00022000 00:0f 1633727 
  /usr/bin/kmod
00623000-00624000 rw-p 00023000 00:0f 1633727 
  /usr/bin/kmod
01c9e000-03e21000 rw-p 00000000 00:00 0 
  [heap]
7f3ec1f2a000-7f3ec1f41000 r-xp 00000000 00:0f 2706024 
  /usr/lib64/libpthread-2.20.so
7f3ec1f41000-7f3ec2140000 ---p 00017000 00:0f 2706024 
  /usr/lib64/libpthread-2.20.so
7f3ec2140000-7f3ec2141000 r--p 00016000 00:0f 2706024 
  /usr/lib64/libpthread-2.20.so
7f3ec2141000-7f3ec2142000 rw-p 00017000 00:0f 2706024 
  /usr/lib64/libpthread-2.20.so
7f3ec2142000-7f3ec2146000 rw-p 00000000 00:00 0
7f3ec214a000-7f3ec22fd000 r-xp 00000000 00:0f 2705998 
  /usr/lib64/libc-2.20.so
7f3ec22fd000-7f3ec24fd000 ---p 001b3000 00:0f 2705998 
  /usr/lib64/libc-2.20.so
7f3ec24fd000-7f3ec2501000 r--p 001b3000 00:0f 2705998 
  /usr/lib64/libc-2.20.so
7f3ec2501000-7f3ec2503000 rw-p 001b7000 00:0f 2705998 
  /usr/lib64/libc-2.20.so
7f3ec2503000-7f3ec2507000 rw-p 00000000 00:00 0
7f3ec250a000-7f3ec2520000 r-xp 00000000 00:0f 2570841 
  /usr/lib64/libgcc_s-4.9.2-20150212.so.1
7f3ec2520000-7f3ec271f000 ---p 00016000 00:0f 2570841 
  /usr/lib64/libgcc_s-4.9.2-20150212.so.1
7f3ec271f000-7f3ec2720000 r--p 00015000 00:0f 2570841 
  /usr/lib64/libgcc_s-4.9.2-20150212.so.1
7f3ec2720000-7f3ec2721000 rw-p 00016000 00:0f 2570841 
  /usr/lib64/libgcc_s-4.9.2-20150212.so.1
7f3ec2722000-7f3ec2737000 r-xp 00000000 00:0f 1510512 
  /usr/lib64/libz.so.1.2.8
7f3ec2737000-7f3ec2936000 ---p 00015000 00:0f 1510512 
  /usr/lib64/libz.so.1.2.8
7f3ec2936000-7f3ec2937000 r--p 00014000 00:0f 1510512 
  /usr/lib64/libz.so.1.2.8
7f3ec2937000-7f3ec2938000 rw-p 00015000 00:0f 1510512 
  /usr/lib64/libz.so.1.2.8
7f3ec293a000-7f3ec295e000 r-xp 00000000 00:0f 1510471 
  /usr/lib64/liblzma.so.5.0.99
7f3ec295e000-7f3ec2b5d000 ---p 00024000 00:0f 1510471 
  /usr/lib64/liblzma.so.5.0.99
7f3ec2b5d000-7f3ec2b5e000 r--p 00023000 00:0f 1510471 
  /usr/lib64/liblzma.so.5.0.99
7f3ec2b5e000-7f3ec2b5f000 rw-p 00024000 00:0f 1510471 
  /usr/lib64/liblzma.so.5.0.99
7f3ec2b62000-7f3ec2b83000 r-xp 00000000 00:0f 2705991 
  /usr/lib64/ld-2.20.so
7f3ec2d83000-7f3ec2d84000 r--p 00021000 00:0f 2705991 
  /usr/lib64/ld-2.20.so
7f3ec2d84000-7f3ec2d85000 rw-p 00022000 00:0f 2705991 
  /usr/lib64/ld-2.20.so
7f3ec2d85000-7f3ec2d86000 rw-p 00000000 00:00 0
7f3ec2d87000-7f3ec2d8d000 rw-p 00000000 00:00 0
7fffa72ea000-7fffa730d000 rw-p 00000000 00:00 0 
  [stack]
7fffa7342000-7fffa7344000 r--p 00000000 00:00 0 
  [vvar]
7fffa7344000-7fffa7346000 r-xp 00000000 00:00 0 
  [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 
  [vsyscall]
./scripts/depmod.sh: Zeile 57: 30419 Abgebrochen 
(Speicherabzug geschrieben) "$DEPMOD" "$@" "$KERNELRELEASE" $SYMBOL_PREFIX
Makefile:1142: recipe for target '_modinst_post' failed
make: *** [_modinst_post] Error 134

Regards,

Alexander Holler