From: Sergei Trofimovich <slyfox@xxxxxxxxxx>
Subject: mm: page_alloc: fix page_poison=1 / INIT_ON_ALLOC_DEFAULT_ON interaction
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.
Link: https://lkml.kernel.org/r/20210714031935.4094114-1-keescook@xxxxxxxxxxxx
Link: https://lore.kernel.org/r/20210712215816.1512739-1-slyfox@xxxxxxxxxx
Fixes: 51cba1ebc60d ("init_on_alloc: Optimize static branches")
Signed-off-by: Sergei Trofimovich <slyfox@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Co-developed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reported-by: Mikhail Morfikov <mmorfikov@xxxxxxxxx>
Reported-by: <bowsingbetee@xxxxx>
Tested-by: <bowsingbetee@xxxxxxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)
--- a/mm/page_alloc.c~mm-page_alloc-fix-page_poison=1-init_on_alloc_default_on-interaction
+++ a/mm/page_alloc.c
@@ -840,21 +840,24 @@ void init_mem_debugging_and_hardening(vo
}
#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;
_
