Commit ef222127 authored by Kees Cook's avatar Kees Cook Committed by liwei
Browse files

x86, relocs: Ignore relocations in .notes section 

stable inclusion
from stable-v5.10.214
commit a4e7ff1a74274e59a2de9bb57236542aa990d20a
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9FNFG
CVE: CVE-2024-26816

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a4e7ff1a74274e59a2de9bb57236542aa990d20a



--------------------------------

[ Upstream commit aaa8736370db1a78f0e8434344a484f9fd20be3b ]

When building with CONFIG_XEN_PV=y, .text symbols are emitted into
the .notes section so that Xen can find the "startup_xen" entry point.
This information is used prior to booting the kernel, so relocations
are not useful. In fact, performing relocations against the .notes
section means that the KASLR base is exposed since /sys/kernel/notes
is world-readable.

To avoid leaking the KASLR base without breaking unprivileged tools that
are expecting to read /sys/kernel/notes, skip performing relocations in
the .notes section. The values readable in .notes are then identical to
those found in System.map.

Reported-by: default avatarGuixiong Wei <guixiongwei@gmail.com>
Closes: https://lore.kernel.org/all/20240218073501.54555-1-guixiongwei@gmail.com/


Fixes: 5ead97c8 ("xen: Core Xen implementation")
Fixes: da1a679c ("Add /sys/kernel/notes")
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarliwei <liwei728@huawei.com>
parent 4e07a69a

arch/x86/tools/relocs.c

+8 −0
Original line number Diff line number Diff line
@@ -596,6 +596,14 @@ static void print_absolute_relocs(void) 
		if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {

			continue;

		}

		/*

		 * Do not perform relocations in .notes section; any

		 * values there are meant for pre-boot consumption (e.g.

		 * startup_xen).

		 */

		if (sec_applies->shdr.sh_type == SHT_NOTE) {

			continue;

		}

		sh_symtab  = sec_symtab->symtab;

		sym_strtab = sec_symtab->link->strtab;

		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {