Message ID | 1380626897-500-1-git-send-email-berrange@redhat.com |
---|---|
State | New |
Headers | show |
"Daniel P. Berrange" <berrange@redhat.com> writes: > From: "Daniel P. Berrange" <berrange@redhat.com> > > If there is no operation driver for the xattr type the > functions return '-1' and set errno to '-EOPNOTSUPP'. > When the calling code sets 'ret = -errno' this turns > into a large positive number. > > In Linux 3.11, the kernel has switched to using 9p > version 9p2000.L, instead of 9p2000.u, which enables > support for xattr operations. This on its own is harmless, > but for another change which makes it request the xattr > with a name 'security.capability'. > > The result is that the guest sees a succesful return > of 95 bytes of data, instead of a failure with errno > set to 95. Since the kernel expects a maximum of 20 > bytes for an xattr return this gets translated to the > unexpected errno ERANGE. > > This all means that when running a binary off a 9p fs > in 3.11 kernels you get a fun result of: > > # ./date > sh: ./date: Numerical result out of range > > The only workaround is to pass 'version=9p2000.u' when > mounting the 9p fs in the guest, to disable all use of > xattrs. > > Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> > --- > hw/9pfs/virtio-9p-xattr.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/hw/9pfs/virtio-9p-xattr.c b/hw/9pfs/virtio-9p-xattr.c > index 90ae565..3fae557 100644 > --- a/hw/9pfs/virtio-9p-xattr.c > +++ b/hw/9pfs/virtio-9p-xattr.c > @@ -36,7 +36,7 @@ ssize_t v9fs_get_xattr(FsContext *ctx, const char *path, > if (xops) { > return xops->getxattr(ctx, path, name, value, size); > } > - errno = -EOPNOTSUPP; > + errno = EOPNOTSUPP; > return -1; > } > > @@ -123,7 +123,7 @@ int v9fs_set_xattr(FsContext *ctx, const char *path, const char *name, > if (xops) { > return xops->setxattr(ctx, path, name, value, size, flags); > } > - errno = -EOPNOTSUPP; > + errno = EOPNOTSUPP; > return -1; > > } > @@ -135,7 +135,7 @@ int v9fs_remove_xattr(FsContext *ctx, > if (xops) { > return xops->removexattr(ctx, path, name); > } > - errno = -EOPNOTSUPP; > + errno = EOPNOTSUPP; > return -1; > > } > -- > 1.8.3.1
01.10.2013 15:28, Daniel P. Berrange пишет: > From: "Daniel P. Berrange" <berrange@redhat.com> > > If there is no operation driver for the xattr type the > functions return '-1' and set errno to '-EOPNOTSUPP'. > When the calling code sets 'ret = -errno' this turns > into a large positive number. > > In Linux 3.11, the kernel has switched to using 9p > version 9p2000.L, instead of 9p2000.u, which enables > support for xattr operations. This on its own is harmless, > but for another change which makes it request the xattr > with a name 'security.capability'. > > The result is that the guest sees a succesful return > of 95 bytes of data, instead of a failure with errno > set to 95. Since the kernel expects a maximum of 20 > bytes for an xattr return this gets translated to the > unexpected errno ERANGE. > > This all means that when running a binary off a 9p fs > in 3.11 kernels you get a fun result of: > > # ./date > sh: ./date: Numerical result out of range > > The only workaround is to pass 'version=9p2000.u' when > mounting the 9p fs in the guest, to disable all use of > xattrs. Thanks, applied to the trivial patches queue. /mjt
diff --git a/hw/9pfs/virtio-9p-xattr.c b/hw/9pfs/virtio-9p-xattr.c index 90ae565..3fae557 100644 --- a/hw/9pfs/virtio-9p-xattr.c +++ b/hw/9pfs/virtio-9p-xattr.c @@ -36,7 +36,7 @@ ssize_t v9fs_get_xattr(FsContext *ctx, const char *path, if (xops) { return xops->getxattr(ctx, path, name, value, size); } - errno = -EOPNOTSUPP; + errno = EOPNOTSUPP; return -1; } @@ -123,7 +123,7 @@ int v9fs_set_xattr(FsContext *ctx, const char *path, const char *name, if (xops) { return xops->setxattr(ctx, path, name, value, size, flags); } - errno = -EOPNOTSUPP; + errno = EOPNOTSUPP; return -1; } @@ -135,7 +135,7 @@ int v9fs_remove_xattr(FsContext *ctx, if (xops) { return xops->removexattr(ctx, path, name); } - errno = -EOPNOTSUPP; + errno = EOPNOTSUPP; return -1; }