Details
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Bug
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Status: Open (View Workflow)
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Major
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Resolution: Unresolved
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10.5, 10.6, 10.7, 10.8, 10.9, 10.10, 10.11, 11.0, 11.1
Description
Recently, MSAN_OPTIONS=poison_in_dtor=1 was enabled by default. This caught some foul play in InnoDB (to be fixed in MDEV-30936) as well as massive amounts of failures in free_root(), because the root->used or root->free lists could be marked as uninitialized in various destructors for objects that are allocated from a MEM_ROOT.
It would be good programming style to make sure that MemorySanitizer does not report any errors when MSAN_OPTIONS=poison_in_dtor=1 is set.
It is possible to work around the errors with the following patch:
diff --git a/mysys/my_alloc.c b/mysys/my_alloc.c
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index aa0182c755e..b9071ad7eee 100644
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--- a/mysys/my_alloc.c
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+++ b/mysys/my_alloc.c
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@@ -415,14 +415,26 @@ void free_root(MEM_ROOT *root, myf MyFlags)
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if (!(MyFlags & MY_KEEP_PREALLOC))
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root->pre_alloc=0;
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+#if __has_feature(memory_sanitizer)
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+ /* Work around MSAN_OPTIONS=poison_in_dtor=1 */
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+ MEM_MAKE_DEFINED(&root->used, sizeof root->used);
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+ MEM_MAKE_DEFINED(&root->free, sizeof root->free);
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+#endif
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+
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for (next=root->used; next ;)
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{
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+#if __has_feature(memory_sanitizer)
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+ MEM_MAKE_DEFINED(&next->next, sizeof next->next);
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+#endif
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old=next; next= next->next ;
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if (old != root->pre_alloc)
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my_free(old);
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}
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for (next=root->free ; next ;)
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{
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+#if __has_feature(memory_sanitizer)
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+ MEM_MAKE_DEFINED(&next->next, sizeof next->next);
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+#endif
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old=next; next= next->next;
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if (old != root->pre_alloc)
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my_free(old); |
I think that explicitly setting MSAN_OPTIONS=poison_in_dtor=0 when using Clang 15 or later is a lesser evil. The above patch could mask other errors as well.
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