linux-kernel - [PATCH] lib/earlycpio: Mark find_cpio_data() __no_stack

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230816100221.12209-1-bp@alien8.de>
Date:   Wed, 16 Aug 2023 12:02:21 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] lib/earlycpio: Mark find_cpio_data() __no_stack_protector

From: "Borislav Petkov (AMD)" <bp@...en8.de>

find_cpio_data() is called by the 32-bit x86 microcode loader while
paging is not yet enabled and the CPU is running off physical addresses.
However, when stack protector is enabled, the compiler adds the stack
protection check for this function:

  c1846480 <find_cpio_data>:
  c1846480:       55                      push   %ebp
  c1846481:       89 e5                   mov    %esp,%ebp
  c1846483:       57                      push   %edi
  ...

  c1846676:       e9 85 fe ff ff          jmp    c1846500 <find_cpio_data+0x80>
  c184667b:       e8 20 9e 02 00          call   c18704a0 <__stack_chk_fail>

which cannot work yet.

Prevent that from happening.

Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
---
 lib/earlycpio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/earlycpio.c b/lib/earlycpio.c
index d2c37d64fd0c..d3efe707c3f7 100644
--- a/lib/earlycpio.c
+++ b/lib/earlycpio.c
@@ -56,8 +56,8 @@ enum cpio_fields {
  *              the match returned an empty filename string.
  */
 
-struct cpio_data find_cpio_data(const char *path, void *data,
-				size_t len,  long *nextoff)
+struct cpio_data __no_stack_protector find_cpio_data(const char *path, void *data,
+						     size_t len,  long *nextoff)
 {
 	const size_t cpio_header_len = 8*C_NFIELDS - 2;
 	struct cpio_data cd = { NULL, 0, "" };
-- 
2.42.0.rc0.25.ga82fb66fed25