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Disable use of UBC_FAULTBUSY in tmpfs_write() for now, 

which brings back zeroing of all new tmpfs data pages.
The existing code that enables this optimization skips the zeroing
in numerous cases where it is needed, resulting in corrupted files
and data leaks from the page's previous identity.
This commit is contained in:
chs 2020-12-13 19:22:02 +00:00
parent 95fe5be41c
commit 81a07a7135
1 changed files with 9 additions and 2 deletions
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11
sys/fs/tmpfs/tmpfs_vnops.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: tmpfs_vnops.c,v 1.144 2020/09/05 16:30:12 riastradh Exp $ */
/* $NetBSD: tmpfs_vnops.c,v 1.145 2020/12/13 19:22:02 chs Exp $ */
/*
* Copyright (c) 2005, 2006, 2007, 2020 The NetBSD Foundation, Inc.
@ -35,7 +35,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: tmpfs_vnops.c,v 1.144 2020/09/05 16:30:12 riastradh Exp $");
__KERNEL_RCSID(0, "$NetBSD: tmpfs_vnops.c,v 1.145 2020/12/13 19:22:02 chs Exp $");
#include <sys/param.h>
#include <sys/dirent.h>
@ -616,12 +616,19 @@ tmpfs_write(void *v)
* of PG_BUSY and the vnode lock).
*/
ubc_flags = UBC_WRITE | UBC_VNODE_FLAGS(vp);
#if 0
/*
* XXX disable use of UBC_FAULTBUSY for now, this check is insufficient
* because it does not zero uninitialized parts of pages in all of
* the cases where zeroing is needed.
*/
if (uio->uio_offset >= oldsize &&
((uio->uio_offset & (PAGE_SIZE - 1)) == 0 ||
((vp->v_vflag & VV_MAPPED) == 0 &&
trunc_page(uio->uio_offset) == trunc_page(oldsize)))) {
ubc_flags |= UBC_FAULTBUSY;
}
#endif
uobj = node->tn_spec.tn_reg.tn_aobj;
error = 0;