| Message ID | 166490685372.401.8724006488941040622.tip-bot2@tip-bot2 |
|---|---|
| State | New |
| Headers | show |
| Series | [tip:,x86/mm] x86/mm: Disable W^X detection and enforcement on 32-bit | expand |
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 20b1e24..efe882c 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -587,6 +587,14 @@ static inline pgprot_t verify_rwx(pgprot_t old, pgprot_t new, unsigned long star { unsigned long end; + /* + * 32-bit has some unfixable W+X issues, like EFI code + * and writeable data being in the same page. Disable + * detection and enforcement there. + */ + if (IS_ENABLED(CONFIG_X86_32)) + return new; + /* Only enforce when NX is supported: */ if (!(__supported_pte_mask & _PAGE_NX)) return new;
The following commit has been merged into the x86/mm branch of tip: Commit-ID: 8c4934f4754057e3577bb1536c6ecc0efa2c966e Gitweb: https://git.kernel.org/tip/8c4934f4754057e3577bb1536c6ecc0efa2c966e Author: Dave Hansen <dave.hansen@linux.intel.com> AuthorDate: Fri, 23 Sep 2022 14:29:45 -07:00 Committer: Dave Hansen <dave.hansen@linux.intel.com> CommitterDate: Mon, 03 Oct 2022 13:12:23 -07:00 x86/mm: Disable W^X detection and enforcement on 32-bit The 32-bit code is in a weird spot. Some 32-bit builds (non-PAE) do not even have NX support. Even PAE builds that support NX have to contend with things like EFI data and code mixed in the same pages where W+X is unavoidable. The folks still running X86_32=y kernels are unlikely to care much about NX. That combined with the fundamental inability fix _all_ of the W+X things means this code had little value on X86_32=y. Disable the checks. Reported-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Darren Hart <dvhart@infradead.org> Cc: Andy Shevchenko <andy@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: x86@kernel.org Cc: linux-efi@vger.kernel.org Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/all/CAMj1kXHcF_iK_g0OZSkSv56Wmr=eQGQwNstcNjLEfS=mm7a06w@mail.gmail.com/ --- arch/x86/mm/pat/set_memory.c | 8 ++++++++ 1 file changed, 8 insertions(+)