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Re: [RFC PATCH v4 2/6] module: preserve Elf information for livepatch modules

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On Tue, 9 Feb 2016, Petr Mladek wrote:

> > +#ifdef CONFIG_KALLSYMS
> > +	/* Make symtab and strtab available prior to module init call */
> > +	mod->num_symtab = mod->core_num_syms;
> > +	mod->symtab = mod->core_symtab;
> > +	mod->strtab = mod->core_strtab;
> > +#endif
> 
> This should be done with module_mutex. Otherwise, it looks racy at least 
> against module_kallsyms_on_each_symbol().

Hmm, if this is the case, the comment describing the locking rules for 
module_mutex should be updated.

> BTW: I wonder why even the original code is not racy for example against 
> module_get_kallsym. It is called without the mutex. This code sets the 
> number of entries before the pointer to the entries.
> 
> Note that the module is in the list even in the UNFORMED state.

module_kallsyms_on_each_symbol() gives up in such case though.

-- 
Jiri Kosina
SUSE Labs

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[RFC PATCH v4 2/6] module: preserve Elf information for livepatch modules Jessica Yu <jeyu@redhat.com> - 2016-02-04 02:20 +0100
  Re: [RFC PATCH v4 2/6] module: preserve Elf information for  livepatch modules Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-08 21:20 +0100
    Re: module: preserve Elf information for livepatch modules Jessica Yu <jeyu@redhat.com> - 2016-02-08 21:40 +0100
  Re: [RFC PATCH v4 2/6] module: preserve Elf information for  livepatch modules Petr Mladek <pmladek@suse.com> - 2016-02-09 09:50 +0100
    Re: [RFC PATCH v4 2/6] module: preserve Elf information for livepatch  modules Jiri Kosina <jikos@kernel.org> - 2016-02-09 11:40 +0100
      Re: [RFC PATCH v4 2/6] module: preserve Elf information for  livepatch modules Petr Mladek <pmladek@suse.com> - 2016-02-09 13:40 +0100
        Re: [RFC PATCH v4 2/6] module: preserve Elf information for livepatch modules Rusty Russell <rusty@rustcorp.com.au> - 2016-02-10 01:30 +0100
  Re: [RFC PATCH v4 2/6] module: preserve Elf information for  livepatch modules Petr Mladek <pmladek@suse.com> - 2016-02-10 17:00 +0100

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