On Fri, 1 Jul 2022 at 16:23, Alexander Potapenko <glider@xxxxxxxxxx> wrote: > > Use hooks from instrumented.h to notify bug detection tools about > usercopy events in get_user() and put_user_size(). > > It's still unclear how to instrument put_user(), which assumes that > instrumentation code doesn't clobber RAX. do_put_user_call() has a comment about KASAN clobbering %ax, doesn't this also apply to KMSAN? If not, could we have a <asm/instrumented.h> that provides helpers to push registers on the stack and pop them back on return? Also it seems the test robot complained about this patch. > Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> > --- > Link: https://linux-review.googlesource.com/id/Ia9f12bfe5832623250e20f1859fdf5cc485a2fce > --- > arch/x86/include/asm/uaccess.h | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h > index 913e593a3b45f..1a8b5a234474f 100644 > --- a/arch/x86/include/asm/uaccess.h > +++ b/arch/x86/include/asm/uaccess.h > @@ -5,6 +5,7 @@ > * User space memory access functions > */ > #include <linux/compiler.h> > +#include <linux/instrumented.h> > #include <linux/kasan-checks.h> > #include <linux/string.h> > #include <asm/asm.h> > @@ -99,11 +100,13 @@ extern int __get_user_bad(void); > int __ret_gu; \ > register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \ > __chk_user_ptr(ptr); \ > + instrument_copy_from_user_before((void *)&(x), ptr, sizeof(*(ptr))); \ > asm volatile("call __" #fn "_%P4" \ > : "=a" (__ret_gu), "=r" (__val_gu), \ > ASM_CALL_CONSTRAINT \ > : "0" (ptr), "i" (sizeof(*(ptr)))); \ > (x) = (__force __typeof__(*(ptr))) __val_gu; \ > + instrument_copy_from_user_after((void *)&(x), ptr, sizeof(*(ptr)), 0); \ > __builtin_expect(__ret_gu, 0); \ > }) > > @@ -248,7 +251,9 @@ extern void __put_user_nocheck_8(void); > > #define __put_user_size(x, ptr, size, label) \ > do { \ > + __typeof__(*(ptr)) __pus_val = x; \ > __chk_user_ptr(ptr); \ > + instrument_copy_to_user(ptr, &(__pus_val), size); \ > switch (size) { \ > case 1: \ > __put_user_goto(x, ptr, "b", "iq", label); \ > @@ -286,6 +291,7 @@ do { \ > #define __get_user_size(x, ptr, size, label) \ > do { \ > __chk_user_ptr(ptr); \ > + instrument_copy_from_user_before((void *)&(x), ptr, size); \ > switch (size) { \ > case 1: { \ > unsigned char x_u8__; \ > @@ -305,6 +311,7 @@ do { \ > default: \ > (x) = __get_user_bad(); \ > } \ > + instrument_copy_from_user_after((void *)&(x), ptr, size, 0); \ > } while (0) > > #define __get_user_asm(x, addr, itype, ltype, label) \ > -- > 2.37.0.rc0.161.g10f37bed90-goog >
