Bug 164353

Summary:	malloc_usable_size() doesn't return a usable size
Product:	[Developer tools] valgrind	Reporter:	Timo Sirainen <tss>
Component:	memcheck	Assignee:	Julian Seward <jseward>
Status:	RESOLVED FIXED
Severity:	normal	CC:	njn
Priority:	NOR
Version First Reported In:	3.3.0
Target Milestone:	---
Platform:	Debian testing
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Timo Sirainen 2008-06-18 02:15:59 UTC

A simple program:

char *mem = malloc(n);
memset(mem, 0, malloc_usable_size(mem));

Results in "invalid write of size x", because malloc_usable_size() returns 8
byte padded values. I think it should return the exact allocated value,
otherwise it just gives pointless errors.

Comment 1 Nicholas Nethercote 2009-06-26 04:11:03 UTC

This was fixed a while ago in SVN.  Thanks for the report.