diff options
| author | Joshua Hahn <joshua.hahnjy@gmail.com> | 2025-12-01 10:07:38 -0800 |
|---|---|---|
| committer | Mike Rapoport (Microsoft) <rppt@kernel.org> | 2025-12-04 19:40:25 +0200 |
| commit | 83c8f7b5e194eaf3fb268c513e23e23e892de8ed (patch) | |
| tree | 3eb3aa6a59d0e0559ac986d4f6d8f46a87a724ac | |
| parent | ac3fd01e4c1efce8f2c054cdeb2ddd2fc0fb150d (diff) | |
mm/mm_init: Introduce a boot parameter for check_pages
Use-after-free and double-free bugs can be very difficult to track down.
The kernel is good at tracking these and preventing bad pages from being
used/created through simple checks gated behind "check_pages_enabled".
Currently, the only ways to enable this flag is by building with
CONFIG_DEBUG_VM, or as a side effect of other checks such as
init_on_{alloc, free}, page_poisoning, or debug_pagealloc among others.
These solutions are powerful, but may often be too coarse in balancing
the performance vs. safety that a user may want, particularly in
latency-sensitive production environments.
Introduce a new boot parameter "check_pages", which enables page checking
with no other side effects. It takes kstrbool-able inputs as an argument
(i.e. 0/1, true/false, on/off, ...). This patch is backwards-compatible;
setting CONFIG_DEBUG_VM still enables page checking.
Acked-by: SeongJae Park <sj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Link: https://patch.msgid.link/20251201180739.2330474-1-joshua.hahnjy@gmail.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 8 | ||||
| -rw-r--r-- | mm/mm_init.c | 10 |
2 files changed, 17 insertions, 1 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 6c42061ca20e..acdc7fbdecac 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -669,6 +669,14 @@ nokmem -- Disable kernel memory accounting. nobpf -- Disable BPF memory accounting. + check_pages= [MM,EARLY] Enable sanity checking of pages after + allocations / before freeing. This adds checks to catch + double-frees, use-after-frees, and other sources of + page corruption by inspecting page internals (flags, + mapcount/refcount, memcg_data, etc.). + Format: { "0" | "1" } + Default: 0 (1 if CONFIG_DEBUG_VM is set) + checkreqprot= [SELINUX] Set initial checkreqprot flag value. Format: { "0" | "1" } See security/selinux/Kconfig help text. diff --git a/mm/mm_init.c b/mm/mm_init.c index 7712d887b696..220b7c6b5fb2 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -2525,6 +2525,14 @@ early_param("init_on_free", early_init_on_free); DEFINE_STATIC_KEY_MAYBE(CONFIG_DEBUG_VM, check_pages_enabled); +static bool check_pages_enabled_early __initdata; + +static int __init early_check_pages(char *buf) +{ + return kstrtobool(buf, &check_pages_enabled_early); +} +early_param("check_pages", early_check_pages); + /* * Enable static keys related to various memory debugging and hardening options. * Some override others, and depend on early params that are evaluated in the @@ -2534,7 +2542,7 @@ DEFINE_STATIC_KEY_MAYBE(CONFIG_DEBUG_VM, check_pages_enabled); static void __init mem_debugging_and_hardening_init(void) { bool page_poisoning_requested = false; - bool want_check_pages = false; + bool want_check_pages = check_pages_enabled_early; #ifdef CONFIG_PAGE_POISONING /* |