37 lines
1.3 KiB
Diff
37 lines
1.3 KiB
Diff
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From 49c165c5a8a40c0ef6a9cee00a81adac2da71533 Mon Sep 17 00:00:00 2001
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From: Ben Wagner <bungeman@chromium.org>
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Date: Tue, 7 Apr 2020 13:12:18 -0400
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Subject: [PATCH 67/68] Don't add to NULL in iterator.
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In C it is undefined to add anything to NULL. Clang recently began
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taking advantage of this and can assume that if anything is added or
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subtracted from a pointer that the pointer can be assumed non-NULL. The
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Address Sanitizer has been updated to report when this happens at
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runtime and produces messages like
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expat/lib/xmlparse.c:6509:23: runtime error: applying zero offset to null pointer
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SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior expat/lib/xmlparse.c:6509:23
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This can be mitigated with 'p ? p + n : NULL' which optimizes to just
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the add in all optimizing compilers, but avoids the undefined behavior.
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---
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lib/xmlparse.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/lib/xmlparse.c b/lib/xmlparse.c
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index 638ea52..849411c 100644
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--- a/lib/xmlparse.c
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+++ b/lib/xmlparse.c
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@@ -6506,7 +6506,7 @@ hashTableInit(HASH_TABLE *p, const XML_Memory_Handling_Suite *ms) {
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static void FASTCALL
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hashTableIterInit(HASH_TABLE_ITER *iter, const HASH_TABLE *table) {
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iter->p = table->v;
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- iter->end = iter->p + table->size;
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+ iter->end = iter->p ? iter->p + table->size : NULL;
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}
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static NAMED *FASTCALL
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--
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1.8.3.1
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