mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions
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>
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@ -23,10 +23,11 @@
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* hit it), 'max' is the address space maximum (and we return
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* -EFAULT if we hit it).
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*/
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static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max)
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static inline long do_strncpy_from_user(char *dst, const char __user *src,
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unsigned long count, unsigned long max)
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{
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const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
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long res = 0;
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unsigned long res = 0;
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/*
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* Truncate 'max' to the user-specified limit, so that
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@ -28,7 +28,7 @@
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static inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max)
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{
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const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
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long align, res = 0;
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unsigned long align, res = 0;
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unsigned long c;
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/*
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@ -42,7 +42,7 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count,
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* Do everything aligned. But that means that we
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* need to also expand the maximum..
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*/
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align = (sizeof(long) - 1) & (unsigned long)src;
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align = (sizeof(unsigned long) - 1) & (unsigned long)src;
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src -= align;
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max += align;
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