Messages in this thread | | | From | Andrey Konovalov <> | Date | Tue, 15 Dec 2020 15:00:52 +0100 | Subject | Re: [PATCH] lkdtm: disable KASAN for rodata.o |
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On Mon, Dec 14, 2020 at 8:15 PM Marco Elver <elver@google.com> wrote: > > Building lkdtm with KASAN and Clang 11 or later results in the following > error when attempting to load the module: > > kernel tried to execute NX-protected page - exploit attempt? (uid: 0) > BUG: unable to handle page fault for address: ffffffffc019cd70 > #PF: supervisor instruction fetch in kernel mode > #PF: error_code(0x0011) - permissions violation > ... > RIP: 0010:asan.module_ctor+0x0/0xffffffffffffa290 [lkdtm] > ... > Call Trace: > do_init_module+0x17c/0x570 > load_module+0xadee/0xd0b0 > __x64_sys_finit_module+0x16c/0x1a0 > do_syscall_64+0x34/0x50 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > The reason is that rodata.o generates a dummy function that lives in > .rodata to validate that .rodata can't be executed; however, Clang 11 > adds KASAN globals support by generating module constructors to > initialize globals redzones. When Clang 11 adds a module constructor to > rodata.o, it is also added to .rodata: any attempt to call it on > initialization results in the above error. > > Therefore, disable KASAN instrumentation for rodata.o. > > Signed-off-by: Marco Elver <elver@google.com> > --- > drivers/misc/lkdtm/Makefile | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile > index c70b3822013f..1c4c7aca0026 100644 > --- a/drivers/misc/lkdtm/Makefile > +++ b/drivers/misc/lkdtm/Makefile > @@ -11,6 +11,7 @@ lkdtm-$(CONFIG_LKDTM) += usercopy.o > lkdtm-$(CONFIG_LKDTM) += stackleak.o > lkdtm-$(CONFIG_LKDTM) += cfi.o > > +KASAN_SANITIZE_rodata.o := n > KASAN_SANITIZE_stackleak.o := n > KCOV_INSTRUMENT_rodata.o := n > > > base-commit: 2c85ebc57b3e1817b6ce1a6b703928e113a90442 > -- > 2.29.2.684.gfbc64c5ab5-goog >
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Thanks for taking care of this!
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