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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, keescook@chromium.org,
	linux-mm@kvack.org, mm-commits@vger.kernel.org,
	nathan@kernel.org, ndesaulniers@google.com,
	torvalds@linux-foundation.org
Subject: [patch 16/18] ubsan: implement __ubsan_handle_alignment_assumption
Date: Thu, 04 Feb 2021 18:32:57 -0800	[thread overview]
Message-ID: <20210205023257.NJnJdyyZk%akpm@linux-foundation.org> (raw)
In-Reply-To: <20210204183135.e123f0d6027529f2cf500cf2@linux-foundation.org>

From: Nathan Chancellor <nathan@kernel.org>
Subject: 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: Nathan Chancellor <nathan@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/ubsan.c |   31 +++++++++++++++++++++++++++++++
 lib/ubsan.h |    6 ++++++
 2 files changed, 37 insertions(+)

--- a/lib/ubsan.c~ubsan-implement-__ubsan_handle_alignment_assumption
+++ a/lib/ubsan.c
@@ -427,3 +427,34 @@ void __ubsan_handle_load_invalid_value(v
 	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);
--- a/lib/ubsan.h~ubsan-implement-__ubsan_handle_alignment_assumption
+++ a/lib/ubsan.h
@@ -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;
_

  parent reply	other threads:[~2021-02-05  2:34 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-05  2:31 incoming Andrew Morton
2021-02-05  2:32 ` [patch 01/18] mm: hugetlbfs: fix cannot migrate the fallocated HugeTLB page Andrew Morton
2021-02-05  2:32 ` [patch 02/18] mm: hugetlb: fix a race between freeing and dissolving the page Andrew Morton
2021-02-05  2:32 ` [patch 03/18] mm: hugetlb: fix a race between isolating and freeing page Andrew Morton
2021-02-05  2:32 ` [patch 04/18] mm: hugetlb: remove VM_BUG_ON_PAGE from page_huge_active Andrew Morton
2021-02-05  2:32 ` [patch 05/18] mm: migrate: do not migrate HugeTLB page whose refcount is one Andrew Morton
2021-02-05  2:32 ` [patch 06/18] mm, compaction: move high_pfn to the for loop scope Andrew Morton
2021-02-05  2:32 ` [patch 07/18] mm/vmalloc: separate put pages and flush VM flags Andrew Morton
2021-02-05  2:32 ` [patch 08/18] init/gcov: allow CONFIG_CONSTRUCTORS on UML to fix module gcov Andrew Morton
2021-02-05  2:32 ` [patch 09/18] mm: thp: fix MADV_REMOVE deadlock on shmem THP Andrew Morton
2021-02-05  2:32 ` [patch 10/18] memblock: do not start bottom-up allocations with kernel_end Andrew Morton
2021-02-05  2:32 ` [patch 11/18] mailmap: fix name/email for Viresh Kumar Andrew Morton
2021-02-05  2:32 ` [patch 12/18] mailmap: add entries for Manivannan Sadhasivam Andrew Morton
2021-02-05  2:32 ` [patch 13/18] mm/filemap: add missing mem_cgroup_uncharge() to __add_to_page_cache_locked() Andrew Morton
2021-02-05  2:32 ` [patch 14/18] kasan: add explicit preconditions to kasan_report() Andrew Morton
2021-02-05  2:32 ` [patch 15/18] kasan: make addr_has_metadata() return true for valid addresses Andrew Morton
2021-02-05  2:32 ` Andrew Morton [this message]
2021-02-05  2:33 ` [patch 17/18] mm: hugetlb: fix missing put_page in gather_surplus_pages() Andrew Morton
2021-02-05  2:33 ` [patch 18/18] MAINTAINERS/.mailmap: use my @kernel.org address Andrew Morton

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