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vfs: Avoid a comparison with an uninitialized field in setutimes()

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Some filesystems, e.g., devfs, do not populate va_birthtime in their
GETATTR implementations.  To handle this, make sure that va_birthtime is
initialized to the quasi-standard value of { VNOVAL, 0 } before calling
VOP_GETATTR.

Reported by:	KMSAN
Reviewed by:	kib
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D31468
This commit is contained in:
Mark Johnston 2021-08-09 13:27:20 -04:00
parent 83952a5baa
commit eca9ac5a32
1 changed files with 8 additions and 4 deletions
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12
sys/kern/vfs_syscalls.c
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@ -3173,15 +3173,19 @@ setutimes(struct thread *td, struct vnode *vp, const struct timespec *ts,
{
struct mount *mp;
struct vattr vattr;
int error, setbirthtime;
int error;
bool setbirthtime;
setbirthtime = false;
vattr.va_birthtime.tv_sec = VNOVAL;
vattr.va_birthtime.tv_nsec = 0;
if ((error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) != 0)
return (error);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
setbirthtime = 0;
if (numtimes < 3 && !VOP_GETATTR(vp, &vattr, td->td_ucred) &&
if (numtimes < 3 && VOP_GETATTR(vp, &vattr, td->td_ucred) == 0 &&
timespeccmp(&ts[1], &vattr.va_birthtime, < ))
setbirthtime = 1;
setbirthtime = true;
VATTR_NULL(&vattr);
vattr.va_atime = ts[0];
vattr.va_mtime = ts[1];