On Fri, Apr 19, 2019 at 09:36:46PM -0700, Randy Dunlap wrote: > On 4/19/19 2:53 PM, akpm@xxxxxxxxxxxxxxxxxxxx wrote: > > The mm-of-the-moment snapshot 2019-04-19-14-53 has been uploaded to > > > > http://www.ozlabs.org/~akpm/mmotm/ > > > > mmotm-readme.txt says > > > > README for mm-of-the-moment: > > > > http://www.ozlabs.org/~akpm/mmotm/ > > > > This is a snapshot of my -mm patch queue. Uploaded at random hopefully > > more than once a week. > > on x86_64: > > CC lib/strncpy_from_user.o > lib/strncpy_from_user.o: warning: objtool: strncpy_from_user()+0x315: call to __ubsan_handle_add_overflow() with UACCESS enabled > CC lib/strnlen_user.o > lib/strnlen_user.o: warning: objtool: strnlen_user()+0x337: call to __ubsan_handle_sub_overflow() with UACCESS enabled Lemme guess, you're using GCC < 8 ? That had a bug where UBSAN considered signed overflow UB when using -fno-strict-overflow or -fwrapv. Now, we could of course allow this symbol, but I found only the below was required to make allyesconfig build without issue. Andy, Linus? (note: the __put_user thing is from this one: drivers/gpu/drm/i915/i915_gem_execbuffer.c: if (unlikely(__put_user(offset, &urelocs[r-stack].presumed_offset))) { where (ptr) ends up non-trivial due to UBSAN) --- diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 22ba683afdc2..c82abd6e4ca3 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -427,10 +427,11 @@ do { \ ({ \ __label__ __pu_label; \ int __pu_err = -EFAULT; \ - __typeof__(*(ptr)) __pu_val; \ - __pu_val = x; \ + __typeof__(*(ptr)) __pu_val = (x); \ + __typeof__(ptr) __pu_ptr = (ptr); \ + __typeof__(size) __pu_size = (size); \ __uaccess_begin(); \ - __put_user_size(__pu_val, (ptr), (size), __pu_label); \ + __put_user_size(__pu_val, __pu_ptr, __pu_size, __pu_label); \ __pu_err = 0; \ __pu_label: \ __uaccess_end(); \ diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c index 58eacd41526c..07045bc4872e 100644 --- a/lib/strncpy_from_user.c +++ b/lib/strncpy_from_user.c @@ -26,7 +26,7 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max) { const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; - long res = 0; + unsigned long res = 0; /* * Truncate 'max' to the user-specified limit, so that diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c index 1c1a1b0e38a5..0729378ad3e9 100644 --- a/lib/strnlen_user.c +++ b/lib/strnlen_user.c @@ -28,7 +28,7 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max) { const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; - long align, res = 0; + unsigned long align, res = 0; unsigned long c; /*
