Author: dim
Date: Sun Dec 18 14:31:11 2016
New Revision: 310228
URL: https://svnweb.freebsd.org/changeset/base/310228
Log:
MFC r310013 (by cperciva):
Check that blkfront devices have a non-zero number of sectors and a
non-zero sector size. Such a device would be a virtual disk of zero
bytes; clearly not useful, and not something we should try to attach.
As a fortuitous side effect, checking that these values are non-zero
here results in them not *becoming* zero later on the function. This
odd behaviour began with r309124 (clang 3.9.0) but is challenging to
debug; making any changes to this function whatsoever seems to affect
the llvm optimizer behaviour enough to make the unexpected zeroing of
the sector_size variable cease.
PR: 215209
Security: The potential for variables to unexpectedly become zero
has worrying consequences for security in general, but
not so much in this particular context.
MFC r310086:
In xbd_connect(), use correct scanf conversion specifiers for the
feature_barrier and feature_flush variables. Otherwise, adjacent
variables on the stack, such as sector_size, may be overwritten, with
disastrous results.
Note that I did not see a good reason to revert the addition of zero
checks introduced in r310013. Better safe than sorry.
PR: 215209
Tested by: royger
Modified:
stable/10/sys/dev/xen/blkfront/blkfront.c
Directory Properties:
stable/10/ (props changed)
Changes in other areas also in this revision:
Modified:
stable/11/sys/dev/xen/blkfront/blkfront.c
stable/9/sys/dev/xen/blkfront/blkfront.c
Directory Properties:
stable/11/ (props changed)
stable/9/ (props changed)
stable/9/sys/ (props changed)
Modified: stable/10/sys/dev/xen/blkfront/blkfront.c
==============================================================================
--- stable/10/sys/dev/xen/blkfront/blkfront.c Sun Dec 18 14:10:24 2016
(r310227)
+++ stable/10/sys/dev/xen/blkfront/blkfront.c Sun Dec 18 14:31:11 2016
(r310228)
@@ -1239,19 +1239,27 @@ xbd_connect(struct xbd_softc *sc)
xenbus_get_otherend_path(dev));
return;
}
+ if ((sectors == 0) || (sector_size == 0)) {
+ xenbus_dev_fatal(dev, 0,
+ "invalid parameters from %s:"
+ " sectors = %lu, sector_size = %lu",
+ xenbus_get_otherend_path(dev),
+ sectors, sector_size);
+ return;
+ }
err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
"physical-sector-size", "%lu", &phys_sector_size,
NULL);
if (err || phys_sector_size <= sector_size)
phys_sector_size = 0;
err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
- "feature-barrier", "%lu", &feature_barrier,
+ "feature-barrier", "%d", &feature_barrier,
NULL);
if (err == 0 && feature_barrier != 0)
sc->xbd_flags |= XBDF_BARRIER;
err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
- "feature-flush-cache", "%lu", &feature_flush,
+ "feature-flush-cache", "%d", &feature_flush,
NULL);
if (err == 0 && feature_flush != 0)
sc->xbd_flags |= XBDF_FLUSH;
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