Bug 16852

Summary:	recvmmsg clobbers const argument
Product:	glibc	Reporter:	Rich Felker <bugdal>
Component:	network	Assignee:	Not yet assigned to anyone <unassigned>
Status:	RESOLVED FIXED
Severity:	normal	CC:	drepper.fsp, fweimer, nodakai
Priority:	P2	Flags:	fweimer: security-
Version:	unspecified
Target Milestone:	2.21
Host:		Target:
Build:		Last reconfirmed:

Description Rich Felker 2014-04-18 01:01:47 UTC

In sysdeps/unix/sysv/linux/recvmmsg.c, the const struct timespec *tmo argument is passed directly to the Linux syscall recvmmsg which overwrites the pointed-to struct with the remaining time. If this behavior is desired, the argument needs to be changed to be a pointer-to-non-const, but the policy elsewhere (in other analogous interfaces) seems to be to suppress the kernel behavior by using a temp copy of the timeout to pass to the kernel.

Comment 1 Florian Weimer 2015-02-18 14:43:10 UTC

Shouldn't the prototype be changed instead because the interface is specific to Linux?

Comment 2 Rich Felker 2015-02-18 18:54:00 UTC

This issue was discussed somewhere else -- I don't recall exactly but it was probably the man pages list or something kernel-related -- and the feeling was that the const in glibc is wrong since this is a Linux-specific interface. I'm okay with removing const and updating documentation to reflect Linux behavior if that's what you prefer. That's what we did in musl.

Comment 3 NODA, Kai 2016-04-10 14:46:01 UTC

Already fixed in 20e5a5f aka glibc-2.21~541