[Bug 259970] sys.kern.coredump_phnum_test.coredump_phnum fails with ASLR on by default

From: <bugzilla-noreply_at_freebsd.org>
Date: Sun, 21 Nov 2021 18:00:04 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=259970

--- Comment #2 from commit-hook@FreeBSD.org ---
A commit in branch main references this bug:

URL:
https://cgit.FreeBSD.org/src/commit/?id=8ec4c5dae32765701ac70811455084efd1570c32

commit 8ec4c5dae32765701ac70811455084efd1570c32
Author:     Ed Maste <emaste@FreeBSD.org>
AuthorDate: 2021-11-21 17:17:20 +0000
Commit:     Ed Maste <emaste@FreeBSD.org>
CommitDate: 2021-11-21 17:57:38 +0000

    Fix coredump_phnum test with ASLR enabled by default

    coredump_phnum intends to generate a core file with many PT_LOAD
    segments.  Previously it called mmap() in a loop with alternating
    protections, relying on each mapping following the previous, to produce
    a core file with many page-sized PT_LOAD segments.  With ASLR on we no
    longer have this property of each mmap() following the previous.

    Instead, perform a single allocation, and then use mprotect() to set
    alternating pages to PROT_READ.

    PR:             259970
    Reported by:    lwhsu, mw
    Reviewed by:    kib
    MFC after:      1 week
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D33070

 tests/sys/kern/coredump_phnum_helper.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

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