Bug 131186

Summary:	writev reports error in (vector[...])
Product:	[Developer tools] valgrind	Reporter:	Magnus Fromreide <valgrind>
Component:	general	Assignee:	Julian Seward <jseward>
Status:	RESOLVED FIXED
Severity:	wishlist	CC:	pjfloyd
Priority:	NOR
Version First Reported In:	3.2.0
Target Milestone:	---
Platform:	Debian testing
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Print the index of the faulty io_vec entry for writev

Description Magnus Fromreide 2006-07-21 22:01:27 UTC

I have a buggy program that calls writev with an io_vec that points to
some uninitialized memory.

Valgrind happily reports that as:

Syscall param writev(vector[...]) points to uninitialised byte(s)

But I think it would be helpful if it told witch io_vec element it is that is faulty

Comment 1 Magnus Fromreide 2006-07-21 22:06:47 UTC

Created attachment 17060 [details]
Print the index of the faulty io_vec entry for writev

With the attached patch the printout becomes:

Syscall param writev(vector[2]) points to uninitialised byte(s)

The drawback is that it increases the run cost significantly.
Another enhancement vould be to fix readv, sendmsg and recvmsg as well.

Comment 2 Paul Floyd 2022-10-12 08:24:14 UTC

I don't see why this should cause much of a slowdown.

commit 2dde5c405b020c96c0595222045475d195939a2b (HEAD -> master, origin/master, origin/HEAD)
Author: Paul Floyd <pjfloyd@wanadoo.fr>
Date:   Wed Oct 12 08:34:51 2022 +0200

    Bug 131186 - writev reports error in (vector[...])
    
    Use the index rather than ...
    Also done for readv.