mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions (29da93fe) · Commits · 戴 / test

Randy reported objtool triggered on his (GCC-7.4) build: lib/strncpy_from_user.o: warning: objtool: strncpy_from_user()+0x315: call to __ubsan_handle_add_overflow() with UACCESS enabled lib/strnlen_user.o: warning: objtool: strnlen_user()+0x337: call to __ubsan_handle_sub_overflow() with UACCESS enabled This is due to UBSAN generating signed-overflow-UB warnings where it should not. Prior to GCC-8 UBSAN ignored -fwrapv (which the kernel uses through -fno-strict-overflow). Make the functions use 'unsigned long' throughout. Reported-by:

Randy Dunlap <rdunlap@infradead.org> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested Acked-by:

Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: luto@kernel.org Link: http://lkml.kernel.org/r/20190424072208.754094071@infradead.org Signed-off-by:

Ingo Molnar <mingo@kernel.org>

lib/strncpy_from_user.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -23,10 +23,11 @@
		* hit it), 'max' is the address space maximum (and we return
		* -EFAULT if we hit it).
		*/
		static inline long do_strncpy_from_user(char dst, const char __user src, long count, unsigned long max)
		static inline long do_strncpy_from_user(char dst, const char __user src,
		unsigned 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

lib/strnlen_user.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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;

		/*
		@@ -42,7 +42,7 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count,
		* Do everything aligned. But that means that we
		* need to also expand the maximum..
		*/
		align = (sizeof(long) - 1) & (unsigned long)src;
		align = (sizeof(unsigned long) - 1) & (unsigned long)src;
		src -= align;
		max += align;

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