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hamt: fix technically undefined behavior

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Bug reported by Bruno Haible in
<https://lists.gnu.org/r/bug-gnulib/2022-04/msg00023.html>.
* lib/hamt.c (entry_insert): Remove technically undefined
behavior when shifting an integer of N bits by N or more bits.
This commit is contained in:
Marc Nieper-Wißkirchen
2022-08-12 16:00:23 +02:00
committed by Bruno Haible
parent cd053975e1
commit ab089716f1
2 changed files with 13 additions and 0 deletions
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ChangeLog
+8
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@@ -1,3 +1,11 @@
2022-08-12 Marc Nieper-Wißkirchen <marc@nieper-wisskirchen.de>
hamt: fix technically undefined behavior
Bug reported by Bruno Haible in
<https://lists.gnu.org/r/bug-gnulib/2022-04/msg00023.html>.
* lib/hamt.c (entry_insert): Remove technically undefined
behavior when shifting an integer of N bits by N or more bits.
2022-08-09 Paul Eggert <eggert@cs.ucla.edu>
verify: port ‘assume’ to C23 non-GCC
lib/hamt.c
+5
View File
@@ -680,6 +680,11 @@ entry_insert (const struct function_table *functions, Hamt_entry *entry,
Hamt_entry *new_entry = copy_entry (*elt_ptr);
if (replace)
*elt_ptr = NULL;
/* We have to take this shortcut as shifting an integer of N
bits by N or more bits triggers undefined behavior.
See: https://lists.gnu.org/archive/html/bug-gnulib/2022-04/msg00023.html. */
if (depth >= _GL_HAMT_MAX_DEPTH)
return (Hamt_entry *) create_populated_bucket (new_entry, copy_entry (entry));
return create_populated_subtrie (new_entry, copy_entry (entry), hash,
(hash_element (functions, entry)
>> (5 * depth)), depth);