linux-kernel - [tip: x86/urgent] x86: Fix .brk attribute in linker script

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Message-ID: <165675566667.15455.2024070946112481051.tip-bot2@tip-bot2>
Date:   Sat, 02 Jul 2022 09:54:26 -0000
From:   "tip-bot2 for Juergen Gross" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Juergen Gross <jgross@...e.com>, Borislav Petkov <bp@...e.de>,
        Josh Poimboeuf <jpoimboe@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86: Fix .brk attribute in linker script

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     7e09ac27f43b382f5fe9bb7c7f4c465ece1f8a23
Gitweb:        https://git.kernel.org/tip/7e09ac27f43b382f5fe9bb7c7f4c465ece1f8a23
Author:        Juergen Gross <jgross@...e.com>
AuthorDate:    Thu, 30 Jun 2022 09:14:41 +02:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Fri, 01 Jul 2022 11:12:43 +02:00

x86: Fix .brk attribute in linker script

Commit in Fixes added the "NOLOAD" attribute to the .brk section as a
"failsafe" measure.

Unfortunately, this leads to the linker no longer covering the .brk
section in a program header, resulting in the kernel loader not knowing
that the memory for the .brk section must be reserved.

This has led to crashes when loading the kernel as PV dom0 under Xen,
but other scenarios could be hit by the same problem (e.g. in case an
uncompressed kernel is used and the initrd is placed directly behind
it).

So drop the "NOLOAD" attribute. This has been verified to correctly
cover the .brk section by a program header of the resulting ELF file.

Fixes: e32683c6f7d2 ("x86/mm: Fix RESERVE_BRK() for older binutils")
Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@...nel.org>
Link: https://lore.kernel.org/r/20220630071441.28576-4-jgross@suse.com
---
 arch/x86/kernel/vmlinux.lds.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 81aba71..9487ce8 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -385,7 +385,7 @@ SECTIONS
 	__end_of_kernel_reserve = .;
 
 	. = ALIGN(PAGE_SIZE);
-	.brk (NOLOAD) : AT(ADDR(.brk) - LOAD_OFFSET) {
+	.brk : AT(ADDR(.brk) - LOAD_OFFSET) {
 		__brk_base = .;
 		. += 64 * 1024;		/* 64k alignment slop space */
 		*(.bss..brk)		/* areas brk users have reserved */