entry_name_utils-inl.h: clear top bit before shifting
Attempting to shift a uint8_t which has the top bit set results in a
value outside of the range allowable for a uint8_t. The process of
converting this value back to a uint8_t triggers ubsan's
implicit-conversion sanitizer.
Ensure the high order bit is stripped before shifting, so that the
shifted value fits into the allowable uint8_t range.
This change is necessary to enable integer sanitization on this code.
Somewhat related to Bug: 122975762
Test: atest ziparchive-tests
Change-Id: I940c8b2828ac88348d80f731274b990e35de6631
diff --git a/libziparchive/entry_name_utils-inl.h b/libziparchive/entry_name_utils-inl.h
index 5fc2fb4..1714586 100644
--- a/libziparchive/entry_name_utils-inl.h
+++ b/libziparchive/entry_name_utils-inl.h
@@ -35,7 +35,7 @@
return false;
} else {
// 2-5 byte sequences.
- for (uint8_t first = byte << 1; first & 0x80; first <<= 1) {
+ for (uint8_t first = (byte & 0x7f) << 1; first & 0x80; first = (first & 0x7f) << 1) {
++i;
// Missing continuation byte..