lkdtm: disable KASAN for rodata.o
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. Link: https://lkml.kernel.org/r/20201214191413.3164796-1-elver@google.com Signed-off-by:Marco Elver <elver@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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4784be28
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