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When opening or closing fifo, ensure that the vnode is locked

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exclusively.  Filesystems are assumed to disable shared locking for
the fifo vnode locks, but some do not.

Reported and tested by:	olgeni
Discussed with:	avg
Sponsored by:   The FreeBSD Foundation
MFC after:	1 week
Approved by:	re (glebius)
This commit is contained in:
Konstantin Belousov 2013-09-13 06:52:23 +00:00
parent 8740a7112e
commit 9bec6325ad
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=255510
1 changed files with 3 additions and 1 deletions
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4
sys/kern/vfs_vnops.c
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@ -267,6 +267,8 @@ vn_open_vnode(struct vnode *vp, int fmode, struct ucred *cred,
return (error);
}
}
if (vp->v_type == VFIFO && VOP_ISLOCKED(vp) != LK_EXCLUSIVE)
vn_lock(vp, LK_UPGRADE | LK_RETRY);
if ((error = VOP_OPEN(vp, fmode, cred, td, fp)) != 0)
return (error);
@ -358,7 +360,7 @@ vn_close(vp, flags, file_cred, td)
struct mount *mp;
int error, lock_flags;
if (!(flags & FWRITE) && vp->v_mount != NULL &&
if (vp->v_type != VFIFO && !(flags & FWRITE) && vp->v_mount != NULL &&
vp->v_mount->mnt_kern_flag & MNTK_EXTENDED_SHARED)
lock_flags = LK_SHARED;
else