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vfs: Add an assertion around name length limits

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Some filesystems assume that they can copy a name component, with length
bounded by NAME_MAX, into a dirent buffer of size MAXNAMLEN.  These
constants have the same value; add a compile-time assertion to that
effect.

Reported by:	Alexey Kulaev <alex.qart@gmail.com>
Reviewed by:	kib
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D29431
This commit is contained in:
Mark Johnston 2021-03-27 13:42:48 -04:00
parent 90d2f7c413
commit 71c160a8f6
1 changed files with 9 additions and 0 deletions
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9
sys/kern/vfs_lookup.c
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@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/dirent.h>
#include <sys/kernel.h>
#include <sys/capsicum.h>
#include <sys/fcntl.h>
@ -747,6 +748,14 @@ needs_exclusive_leaf(struct mount *mp, int flags)
return (0);
}
/*
* Various filesystems expect to be able to copy a name component with length
* bounded by NAME_MAX into a directory entry buffer of size MAXNAMLEN. Make
* sure that these are the same size.
*/
_Static_assert(MAXNAMLEN == NAME_MAX,
"MAXNAMLEN and NAME_MAX have different values");
/*
* Search a pathname.
* This is a very central and rather complicated routine.