Re: [PATCH] ia64: module: fix symbolizer crash on fdescr

[John Paul Adrian Glaubitz]

Hi Sergei!

On 4/3/21 9:48 AM, Sergei Trofimovich wrote:
> Noticed failure as a crash on ia64 when tried to symbolize all
> backtraces collected by page_owner=on:
> 
>     $ cat /sys/kernel/debug/page_owner
>     <oops>
> 
>     CPU: 1 PID: 2074 Comm: cat Not tainted 5.12.0-rc4 #226
>     Hardware name: hp server rx3600, BIOS 04.03 04/08/2008
>     ip is at dereference_module_function_descriptor+0x41/0x100
> 
> Crash happens at dereference_module_function_descriptor() due to
> use-after-free when dereferencing ".opd" section header.
> 
> All section headers are already freed after module is laoded
> successfully.
> 
> To keep symbolizer working the change stores ".opd" address
> and size after module is relocated to a new place and before
> section headers are discarded.
> 
> To make similar errors less obscure module_finalize() now
> zeroes out all variables relevant to module loading only.

Typo: s/zeroes/zero/.

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@xxxxxxxxxx
`. `'   Freie Universitaet Berlin - glaubitz@xxxxxxxxxxxxxxxxxxx
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913