From: Kees Cook <keescook@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>,
Sergei Trofimovich <slyfox@gentoo.org>,
Alexander Potapenko <glider@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Vlastimil Babka <vbabka@suse.cz>,
linux-mm@kvack.org, bowsingbetee@pm.me,
Mikhail Morfikov <mmorfikov@gmail.com>,
stable@vger.kernelo.org, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: [PATCH v2] mm: page_alloc: Fix page_poison=1 / INIT_ON_ALLOC_DEFAULT_ON interaction
Date: Tue, 13 Jul 2021 20:19:35 -0700 [thread overview]
Message-ID: <20210714031935.4094114-1-keescook@chromium.org> (raw)
From: Sergei Trofimovich <slyfox@gentoo.org>
To reproduce the failure we need the following system:
- kernel command: page_poison=1 init_on_free=0 init_on_alloc=0
- kernel config:
* CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y
* CONFIG_INIT_ON_FREE_DEFAULT_ON=y
* CONFIG_PAGE_POISONING=y
0000000085629bdd: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
0000000022861832: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000000c597f5b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
CPU: 11 PID: 15195 Comm: bash Kdump: loaded Tainted: G U O 5.13.1-gentoo-x86_64 #1
Hardware name: System manufacturer System Product Name/PRIME Z370-A, BIOS 2801 01/13/2021
Call Trace:
dump_stack+0x64/0x7c
__kernel_unpoison_pages.cold+0x48/0x84
post_alloc_hook+0x60/0xa0
get_page_from_freelist+0xdb8/0x1000
__alloc_pages+0x163/0x2b0
__get_free_pages+0xc/0x30
pgd_alloc+0x2e/0x1a0
? dup_mm+0x37/0x4f0
mm_init+0x185/0x270
dup_mm+0x6b/0x4f0
? __lock_task_sighand+0x35/0x70
copy_process+0x190d/0x1b10
kernel_clone+0xba/0x3b0
__do_sys_clone+0x8f/0xb0
do_syscall_64+0x68/0x80
? do_syscall_64+0x11/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
Before the 51cba1eb ("init_on_alloc: Optimize static branches")
init_on_alloc never enabled static branch by default. It could
only be enabed explicitly by init_mem_debugging_and_hardening().
But after the 51cba1eb static branch could already be enabled
by default. There was no code to ever disable it. That caused
page_poison=1 / init_on_free=1 conflict.
This change extends init_mem_debugging_and_hardening() to also
disable static branch disabling.
CC: Alexander Potapenko <glider@google.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Vlastimil Babka <vbabka@suse.cz>
CC: linux-mm@kvack.org
Reported-by: bowsingbetee@pm.me
Reported-by: Mikhail Morfikov <mmorfikov@gmail.com>
Fixes: 51cba1ebc60d ("init_on_alloc: Optimize static branches")
Cc: stable@vger.kernelo.org
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Link: https://lore.kernel.org/r/20210712215816.1512739-1-slyfox@gentoo.org
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
mm/page_alloc.c | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3b97e17806be..1f19365bc158 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -840,21 +840,24 @@ void init_mem_debugging_and_hardening(void)
}
#endif
- if (_init_on_alloc_enabled_early) {
- if (page_poisoning_requested)
- pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
- "will take precedence over init_on_alloc\n");
- else
- static_branch_enable(&init_on_alloc);
- }
- if (_init_on_free_enabled_early) {
- if (page_poisoning_requested)
- pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
- "will take precedence over init_on_free\n");
- else
- static_branch_enable(&init_on_free);
+ if ((_init_on_alloc_enabled_early || _init_on_free_enabled_early) &&
+ page_poisoning_requested) {
+ pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
+ "will take precedence over init_on_alloc and init_on_free\n");
+ _init_on_alloc_enabled_early = false;
+ _init_on_free_enabled_early = false;
}
+ if (_init_on_alloc_enabled_early)
+ static_branch_enable(&init_on_alloc);
+ else
+ static_branch_disable(&init_on_alloc);
+
+ if (_init_on_free_enabled_early)
+ static_branch_enable(&init_on_free);
+ else
+ static_branch_disable(&init_on_free);
+
#ifdef CONFIG_DEBUG_PAGEALLOC
if (!debug_pagealloc_enabled())
return;
--
2.30.2
next reply other threads:[~2021-07-14 3:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-14 3:19 Kees Cook [this message]
2021-07-14 3:21 ` [PATCH v2] mm: page_alloc: Fix page_poison=1 / INIT_ON_ALLOC_DEFAULT_ON interaction Kees Cook
2021-07-14 7:55 ` David Hildenbrand
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