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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 4E58416001A X-Stat-Signature: bn1x1sfp9q4exmhqq9xmc1prz6bkm1t5 X-Rspam-User: X-HE-Tag: 1764752502-274503 X-HE-Meta: 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 Pcp1pmG8 bj5qEomEJCD3WM9ayCC5dxE61Nuy8r+TtKXBVLwPsgI4jNaQMs8xaBRU2fWiIBXXZ8ITU5LBaFer8p8+l0rR7rXNANjGoR0ybcUPvUGbYiLEiFZZhyIkeu9OguLGdLWBAYJ/t39AvsK/UMOhnJvk2S8GMoESWi3+00275WhkpGlOdpL9xIVP8+lDOpwUeVp/bjxp68Pdr4sLcDMAs4fnb+evhw0jTCaBRT9+NlDi94UTu6OizrBStHGI669wJMq1qzwvcSTcXPPEcUPqCZw8d8HP0xCMlffjI0MnypbiznH/sB5m6NbGBwksCojzfpON1W61NHnm8IhnPsoIXgGQZmln3+vTeJ5UQaqBvkUQS4+kOBjyuylcTWTwZ6II5tLtUXEUDK18X06vdiab8XEIogP9adJ4JenOc8hOybzCHh7AE8bA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 01/12/25 11:37 PM, Joshua Hahn wrote: > 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 > Acked-by: Michal Hocko > Signed-off-by: Joshua Hahn > --- > v2 --> v3: > - Dropped the second patch. I may pursue it at another time : -) > - Variable renaming (dropping leading _) and cleaner check in > mem_debugging_and_hardening_init, as suggested by Mike Rapoport > v1 --> v2: > - Changed check_pages from a build config into a boot config, as suggested > by Vlastimil. > - Introduced the second patch, which decouples page checking from > init_on_page_alloc and init_on_page_free. > --- > Documentation/admin-guide/kernel-parameters.txt | 8 ++++++++ > mm/mm_init.c | 10 +++++++++- > 2 files changed, 17 insertions(+), 1 deletion(-) > > 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 c6812b4dbb2e..fc2a6f1e518f 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 > /* LGTM. Also a very nice write up for the commit message explaining the new kernel parameter rationale comprehensively. Reviewed-by: Anshuman Khandual