Re: [PATCH] elf: ldconfig should skip temporary files created by package managers

[Florian Weimer <fweimer@redhat.com>]

* Adhemerval Zanella Netto:

> On 20/10/23 09:29, Florian Weimer wrote:
>> This avoids crashes due to partially written files, after a package
>> update is interrupted.
>
> It seems kinda unreliable a tool create temporary files on the libdir,
> although we alrady handle for prelinkk so it makes sense to extend to
> other program as well.  Maybe another option would to proper parse the 
> file header and only handle ELF files, so ldconfig is not bounded to
> name patterns.

The files look like ELF files, but a truncated, so that we get SIGBUS
because the mapping we access is only halfway there.

>> +  /* Skip temporary files created by dpkg.  */
>> +  if (len > 4 && memcmp (name + len - 4, ".tmp", 4) == 0)
>
> Wouldn't this potentially read out the bounds for sizes [5, 8)? Maybe
> just use strcmp?

I don't see how.

   ABCDE
        ^ name + len
    ^ name + len - 4
    .tmp

Looks okay to me?

Thanks,
Florian