[SOLVED] Weird kernel Versioning error with Virtualbox-kernel. Sed magic needed?

business_kid · 05-04-2015, 02:51 PM

From the Slackbuilds I have virtualbox and virtualbox-kernel installed. The modules will not load "Exec Format Error"

The kernel is the Linux stable git 3.19.0-rc6. The error dmesg shows is

Code:

[86788.162754] vboxdrv: version magic '3.19.0 SMP mod_unload ' should be '3.19.0-rc6 SMP mod_unload '

The modules are installed in /lib/modules/3.19.0-rc6 but a hex editor reveals they have the version "3.19.0 SMP mod_unload" internally. There's a string of 0x00 after the kernel version.

sed 's/3.19.0 SMP mod_unload/3.19.0-rc6 SMP mod_unload/' -i <file> produces a length error, so I need to take out 4 0x00 characters as well. Ideas anyone? My hex reader, dhex doesn't seem to do edits.

mancha · 05-04-2015, 02:57 PM

OK, misread the question initially (coffee time).

You can use:

Code:

$ sed -i -e 's/3.19.0 SMP mod_unload\x00\x00\x00\x00/3.19.0-rc6 SMP mod_unload/g' <file>

--mancha

ppr:kut · 05-04-2015, 04:14 PM

My take on this is that the kernel module is compiled against a different kernel than the running one. Did you try recompiling?

business_kid · 05-05-2015, 06:55 AM

@ppr:kut: No, same kernel, but a Linus stable git source, not a normal version

@mancha: Nice try, but it resolutely refused to alter the thing. The syntax is probably ok, but sed didn't like the mix of ascii & hex, or something. I tried it every way I could think of, .bak files > .ko files, also escapes on the full stops (3\.19\.0) but to no avail. Searching for text in a binary file didn't really work. I had to get up the ascii table and search for 33 2e 31 39 2e 30 in the hex search of dhex to find it.

Then I discovered dhex does do edits and it was just that I never really examined it. It needs a console to be happy, not an xterm. but I laboriously altered the things (no copy & paste for hex codes, only the search bar).Installing Fedora Electronic spin while I write.

mancha · 05-05-2015, 12:22 PM

Quote:

Originally Posted by business_kid

@mancha: Nice try, but it resolutely refused to alter the thing. The syntax is probably ok, but sed didn't like the mix of ascii & hex, or something.

Strange. Works for me:

Code:

$ wc -c b_kid.txt
33 b_kid.txt

$ hexdump -C b_kid.txt
00000000  42 45 47 49 4e 33 2e 31  39 2e 30 20 53 4d 50 20  |BEGIN3.19.0 SMP |
00000010  6d 6f 64 5f 75 6e 6c 6f  61 64 00 00 00 00 45 4e  |mod_unload....EN|
00000020  44                                                |D|

$ sed -i -e 's/3.19.0 SMP mod_unload\x00\x00\x00\x00/3.19.0-rc6 SMP mod_unload/' b_kid.txt

$ wc -c b_kid.txt
33 b_kid.txt

$ hexdump -C b_kid.txt
00000000  42 45 47 49 4e 33 2e 31  39 2e 30 2d 72 63 36 20  |BEGIN3.19.0-rc6 |
00000010  53 4d 50 20 6d 6f 64 5f  75 6e 6c 6f 61 64 45 4e  |SMP mod_unloadEN|
00000020  44                                                |D|

Though, as you said, to be entirely proper we should escape the periods in our sed (i.e. sed -i -e 's/3\.19\.0 SMP mod_unload\x00\x00\x00\x00/3.19.0-rc6 SMP mod_unload/').

--mancha

business_kid · 05-05-2015, 01:16 PM

I have uploaded one of the unmodified modules here
https://onedrive.live.com/?cid=99361...4096ff2c07!208

It doesn't work for me, and I had root and farted with perms and everything. No go. I am pretty sure the problem was in the 'find' not the write.

mancha · 05-05-2015, 01:40 PM

Looking at the actual file helped a great deal. Basically, there's a space between "mod_unload" and the 0x00's that needs to be
accounted for. With that change, sed works as expected:

Code:

sed -i.orig -e 's/3\.19\.0 SMP mod_unload \x00\x00\x00\x00/3.19.0-rc6 SMP mod_unload /g' vboxdrv.ko

--mancha

business_kid · 05-05-2015, 03:34 PM

You're talking about the space at the end? the 0x20? Yes, that is sinnificant, because this string

Code:

3.19.0 SMP mod_unload\x00\x00\x00\x00

is actually 3.19.0 SMP mod_unload\x20\x00\x00\x00\x00
So it figures. . . And I thought I just had bad breadth or something.