Bug#1085762: commit identified

[Ulrich Teichert <ulrich.teichert@kumkeo.de>]

Hi,

I ran a lengthy git bisect yesterday and it's this commit on the stable kernel git
which causes the issue:

b0cde867b80a5e81fcbc0383e138f5845f2005ee is the first bad commit
commit b0cde867b80a5e81fcbc0383e138f5845f2005ee
Author: Kees Cook <keescook@chromium.org>
Date:   Fri Feb 16 22:25:43 2024 -0800
    x86: Increase brk randomness entropy for 64-bit systems
    [ Upstream commit 44c76825d6eefee9eb7ce06c38e1a6632ac7eb7d ]
    In commit c1d171a00294 ("x86: randomize brk"), arch_randomize_brk() was
    defined to use a 32MB range (13 bits of entropy), but was never increased
    when moving to 64-bit. The default arch_randomize_brk() uses 32MB for
    32-bit tasks, and 1GB (18 bits of entropy) for 64-bit tasks.
    Update x86_64 to match the entropy used by arm64 and other 64-bit
    architectures.
    Reported-by: y0un9n132@gmail.com
    Signed-off-by: Kees Cook <keescook@chromium.org>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Acked-by: Jiri Kosina <jkosina@suse.com>
    Closes: https://lore.kernel.org/linux-hardening/CA+2EKTVLvc8hDZc+2Yhwmus=dzOUG5E4gV7ayCbu0MPJTZzWkw@mail.gmail.com/
    Link: https://lore.kernel.org/r/20240217062545.1631668-1-keescook@chromium.org
    Signed-off-by: Sasha Levin <sashal@kernel.org>

When I revert it, I can run pbuilder for ARM64 builds all day and it never crashes.

HTH,
Uli

Mit freundlichen Grüßen / Kind regards

Dipl.-Inform. Ulrich Teichert
Senior Software Developer

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