RESOLVED FIXED310770
utf8Buffer() in SharedBuffer.h allocates too much memory for 8-bit strings 
https://bugs.webkit.org/show_bug.cgi?id=310770
Summary utf8Buffer() in SharedBuffer.h allocates too much memory for 8-bit strings
Chris Dumez
Reported 2026-03-25 22:33:27 PDT
Latin1 characters (0x80-0xFF) encode as at most 2 UTF-8 bytes; ASCII (0x00-0x7F) as 1 byte. So length * 2 is sufficient for 8-bit strings. The 3x multiplier is only needed for 16-bit strings (a single BMP codepoint can be 3 UTF-8 bytes). Additionally, Vector<uint8_t> buffer(length * 3) zero-initializes the entire allocation, so the waste is both allocation and initialization.
Attachments
Add attachment proposed patch, testcase, etc.
Chris Dumez
Comment 1 2026-03-25 22:35:17 PDT
Pull request: https://github.com/WebKit/WebKit/pull/61376
EWS
Comment 2 2026-03-26 06:22:29 PDT
Committed 309984@main (65bc0fda9edd): <https://commits.webkit.org/309984@main> Reviewed commits have been landed. Closing PR #61376 and removing active labels.
Radar WebKit Bug Importer
Comment 3 2026-03-26 06:23:13 PDT
<rdar://problem/173402781>
Note You need to log in before you can comment on or make changes to this bug.