Bug 215734 - shared object loaded very low in memory ARM 32bit with kernel 5.17.0

* Bug 215734 - shared object loaded very low in memory ARM 32bit with kernel 5.17.0
@ 2022-03-31  6:17 Thorsten Leemhuis
  2022-04-09 11:52 ` Thorsten Leemhuis
  2022-04-16  4:42 ` Bug 215734 - shared object loaded very low in memory ARM 32bit with kernel 5.17.0 #forregzbot Thorsten Leemhuis
  0 siblings, 2 replies; 4+ messages in thread
From: Thorsten Leemhuis @ 2022-03-31  6:17 UTC (permalink / raw)
  To: H.J. Lu
  Cc: regressions, Linux Kernel Mailing List, Chris Kennelly, Al Viro,
	Alexey Dobriyan, Song Liu, David Rientjes, Ian Rogers,
	Hugh Dickins, Suren Baghdasaryan, Sandeep Patil, Fangrui Song,
	Nick Desaulniers, Kirill A. Shutemov, Mike Kravetz, Shuah Khan,
	Andrew Morton

Hi, this is your Linux kernel regression tracker.

I noticed a regression report in bugzilla.kernel.org that afaics nobody
acted upon since it was reported about a week ago, that's why I decided
to forward it to the lists and all people that seemed to be relevant
here. Note, this is the second regression report referencin a commit
from H.J. Lu as culprit (9630f0d60fec ("fs/binfmt_elf: use PT_LOAD
p_align values for static PIE")). I forwarded the first one on Monday
already, but seems nothing happened:
https://lore.kernel.org/all/cb5b81bd-9882-e5dc-cd22-54bdbaaefbbc@leemhuis.info/

Anyway, to get back to the latest report. To quote from
https://bugzilla.kernel.org/show_bug.cgi?id=215734 :

>  Jan Palus 2022-03-24 10:17:02 UTC
> 
> This is a followup to https://sourceware.org/bugzilla/show_bug.cgi?id=28990 where ld.so --verify segfault was reported on binaries > 4MB.
> 
> It appears that starting with kernel 5.17.0 shared object is loaded in the begging of address space at least on 32-bit ARM:
> 
> /proc/<pid>/maps just before mmap (5.17):
> 00400000-00429000 r-xp 00000000 b3:02 393320     /lib/ld-linux-armhf.so.3
> 00439000-0043c000 rw-p 00029000 b3:02 393320     /lib/ld-linux-armhf.so.3
> 76ffd000-76ffe000 r-xp 00000000 00:00 0          [sigpage]
> 76ffe000-76fff000 r--p 00000000 00:00 0          [vvar]
> 76fff000-77000000 r-xp 00000000 00:00 0          [vdso]
> 7efdf000-7f000000 rw-p 00000000 00:00 0          [stack]
> ffff0000-ffff1000 r-xp 00000000 00:00 0          [vectors]
> 
> causing segfaults when mmaping large binaries at fixed address 0x10000 (ie done by ld.so --verify used by ldd).
> 
> By comparison it is not the case for kernel 5.16.8:
> 
> /proc/<pid>/maps just before mmap (5.16):
> 76fc4000-76fed000 r-xp 00000000 b3:02 393320     /lib/ld-linux-armhf.so.3
> 76ffa000-76ffb000 r-xp 00000000 00:00 0          [sigpage]
> 76ffb000-76ffc000 r--p 00000000 00:00 0          [vvar]
> 76ffc000-76ffd000 r-xp 00000000 00:00 0          [vdso]
> 76ffd000-77000000 rw-p 00029000 b3:02 393320     /lib/ld-linux-armhf.so.3
> 7efdf000-7f000000 rw-p 00000000 00:00 0          [stack]
> ffff0000-ffff1000 r-xp 00000000 00:00 0          [vectors]
> 
> [reply] [−] Comment 1 Jan Palus 2022-03-29 22:14:12 UTC
> 
> First bad commit appears to be:
> 
> From: "H.J. Lu" <hjl.tools@gmail.com>
> Date: Wed, 19 Jan 2022 18:09:40 -0800
> Subject: fs/binfmt_elf: use PT_LOAD p_align values for static PIE
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9630f0d60fec5fbcaa4435a66f75df1dc9704b66
> 

Could somebody take a look into this? Or was this discussed somewhere
else already? Or even fixed?

Anyway, to get this tracked:

#regzbot introduced: 9630f0d60fec5fbcaa4435a66f75df1dc9704b6
#regzbot from: Jan Palus <jpalus@fastmail.com>
#regzbot title: shared object loaded very low in memory ARM 32bit
causing segfaults on binaries > 4MB
#regzbot link: https://bugzilla.kernel.org/show_bug.cgi?id=215734

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)

P.S.: As the Linux kernel's regression tracker I'm getting a lot of
reports on my table. I can only look briefly into most of them and lack
knowledge about most of the areas they concern. I thus unfortunately
will sometimes get things wrong or miss something important. I hope
that's not the case here; if you think it is, don't hesitate to tell me
in a public reply, it's in everyone's interest to set the public record
straight.

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