Commit 28abcc96 authored by Nathan Chancellor's avatar Nathan Chancellor Committed by Linus Torvalds
Browse files

ubsan: implement __ubsan_handle_alignment_assumption 

When building ARCH=mips 32r2el_defconfig with CONFIG_UBSAN_ALIGNMENT:

  ld.lld: error: undefined symbol: __ubsan_handle_alignment_assumption
     referenced by slab.h:557 (include/linux/slab.h:557)
                   main.o:(do_initcalls) in archive init/built-in.a
     referenced by slab.h:448 (include/linux/slab.h:448)
                   do_mounts_rd.o:(rd_load_image) in archive init/built-in.a
     referenced by slab.h:448 (include/linux/slab.h:448)
                   do_mounts_rd.o:(identify_ramdisk_image) in archive init/built-in.a
     referenced 1579 more times

Implement this for the kernel based on LLVM's
handleAlignmentAssumptionImpl because the kernel is not linked against
the compiler runtime.

Link: https://github.com/ClangBuiltLinux/linux/issues/1245
Link: https://github.com/llvm/llvm-project/blob/llvmorg-11.0.1/compiler-rt/lib/ubsan/ubsan_handlers.cpp#L151-L190
Link: https://lkml.kernel.org/r/20210127224451.2587372-1-nathan@kernel.org


Signed-off-by: default avatarNathan Chancellor <nathan@kernel.org>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b99acdcb

lib/ubsan.c

+31 −0
Original line number Diff line number Diff line
@@ -427,3 +427,34 @@ void __ubsan_handle_load_invalid_value(void *_data, void *val) 
	ubsan_epilogue();

}

EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);



void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,

					 unsigned long align,

					 unsigned long offset);

void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,

					 unsigned long align,

					 unsigned long offset)

{

	struct alignment_assumption_data *data = _data;

	unsigned long real_ptr;



	if (suppress_report(&data->location))

		return;



	ubsan_prologue(&data->location, "alignment-assumption");



	if (offset)

		pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",

		       align, offset, data->type->type_name);

	else

		pr_err("assumption of %lu byte alignment for pointer of type %s failed",

		       align, data->type->type_name);



	real_ptr = ptr - offset;

	pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",

	       offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),

	       real_ptr & (align - 1));



	ubsan_epilogue();

}

EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);

lib/ubsan.h

+6 −0
Original line number Diff line number Diff line
@@ -78,6 +78,12 @@ struct invalid_value_data { 
	struct type_descriptor *type;

};



struct alignment_assumption_data {

	struct source_location location;

	struct source_location assumption_location;

	struct type_descriptor *type;

};



#if defined(CONFIG_ARCH_SUPPORTS_INT128)

typedef __int128 s_max;

typedef unsigned __int128 u_max;