linux-kernel - [PATCH] lockdep: Fix static memory detection even more

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: <ZNep5EcYskP9HtGD@p100>
Date:   Sat, 12 Aug 2023 17:48:52 +0200
From:   Helge Deller <deller@....de>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org, linux-parisc@...r.kernel.org,
        Guenter Roeck <linux@...ck-us.net>,
        Borislav Petkov <bp@...e.de>,
        Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH] lockdep: Fix static memory detection even more

On the parisc architecture, lockdep reports for all static objects which
are in the __initdata section (e.g. "setup_done" in devtmpfs,
"kthreadd_done" in init/main.c) this warning:

	INFO: trying to register non-static key.

The warning itself is wrong, because those objects are in the __initdata
section, but the section itself is on parisc outside of range from
_stext to _end, which is why the static_obj() functions returns a wrong
answer.

While fixing this issue, I noticed that the whole existing check can
be simplified a lot.
Instead of checking against the _stext and _end symbols (which include
code areas too) just check for the .data and .bss segments (since we check a
data object). This can be done with the existing is_kernel_core_data()
macro.

In addition objects in the __initdata section can be checked with
init_section_contains().

This partly reverts and simplifies commit bac59d18c701 ("x86/setup: Fix static
memory detection").

Tested on x86-64 and parisc.

Signed-off-by: Helge Deller <deller@....de>
Fixes: bac59d18c701 ("x86/setup: Fix static memory detection")

---

diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h
index a6e8373a5170..3fa87e5e11ab 100644
--- a/arch/x86/include/asm/sections.h
+++ b/arch/x86/include/asm/sections.h
@@ -2,8 +2,6 @@
 #ifndef _ASM_X86_SECTIONS_H
 #define _ASM_X86_SECTIONS_H

-#define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed
-
 #include <asm-generic/sections.h>
 #include <asm/extable.h>

@@ -18,20 +16,4 @@ extern char __end_of_kernel_reserve[];

 extern unsigned long _brk_start, _brk_end;

-static inline bool arch_is_kernel_initmem_freed(unsigned long addr)
-{
-	/*
-	 * If _brk_start has not been cleared, brk allocation is incomplete,
-	 * and we can not make assumptions about its use.
-	 */
-	if (_brk_start)
-		return 0;
-
-	/*
-	 * After brk allocation is complete, space between _brk_end and _end
-	 * is available for allocation.
-	 */
-	return addr >= _brk_end && addr < (unsigned long)&_end;
-}
-
 #endif	/* _ASM_X86_SECTIONS_H */
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 111607d91489..957b785d0b59 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -819,34 +819,20 @@ static int very_verbose(struct lock_class *class)
  * Is this the address of a static object:
  */
 #ifdef __KERNEL__
-/*
- * Check if an address is part of freed initmem. After initmem is freed,
- * memory can be allocated from it, and such allocations would then have
- * addresses within the range [_stext, _end].
- */
-#ifndef arch_is_kernel_initmem_freed
-static int arch_is_kernel_initmem_freed(unsigned long addr)
-{
-	if (system_state < SYSTEM_FREEING_INITMEM)
-		return 0;
-
-	return init_section_contains((void *)addr, 1);
-}
-#endif
-
 static int static_obj(const void *obj)
 {
-	unsigned long start = (unsigned long) &_stext,
-		      end   = (unsigned long) &_end,
-		      addr  = (unsigned long) obj;
+	unsigned long addr = (unsigned long) obj;

-	if (arch_is_kernel_initmem_freed(addr))
-		return 0;
+	if (is_kernel_core_data(addr))
+		return 1;

 	/*
-	 * static variable?
+	 * in initdata section and used during bootup only?
+	 * NOTE: On some platforms the initdata section is
+	 * outside of the _stext ... _end range.
 	 */
-	if ((addr >= start) && (addr < end))
+	if (system_state < SYSTEM_FREEING_INITMEM &&
+		init_section_contains((void *)addr, 1))
 		return 1;

 	/*