bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 136 insertions, 0 deletions

diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig
new file mode 100644
index 000000000..2ac67e04a
--- /dev/null
+++ b/fs/overlayfs/Kconfig
@@ -0,0 +1,136 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config OVERLAY_FS
+	tristate "Overlay filesystem support"
+	select FS_STACK
+	select EXPORTFS
+	help
+	  An overlay filesystem combines two filesystems - an 'upper' filesystem
+	  and a 'lower' filesystem.  When a name exists in both filesystems, the
+	  object in the 'upper' filesystem is visible while the object in the
+	  'lower' filesystem is either hidden or, in the case of directories,
+	  merged with the 'upper' object.
+
+	  For more information see Documentation/filesystems/overlayfs.rst
+
+config OVERLAY_FS_REDIRECT_DIR
+	bool "Overlayfs: turn on redirect directory feature by default"
+	depends on OVERLAY_FS
+	help
+	  If this config option is enabled then overlay filesystems will use
+	  redirects when renaming directories by default.  In this case it is
+	  still possible to turn off redirects globally with the
+	  "redirect_dir=off" module option or on a filesystem instance basis
+	  with the "redirect_dir=off" mount option.
+
+	  Note, that redirects are not backward compatible.  That is, mounting
+	  an overlay which has redirects on a kernel that doesn't support this
+	  feature will have unexpected results.
+
+	  If unsure, say N.
+
+config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW
+	bool "Overlayfs: follow redirects even if redirects are turned off"
+	default y
+	depends on OVERLAY_FS
+	help
+	  Disable this to get a possibly more secure configuration, but that
+	  might not be backward compatible with previous kernels.
+
+	  If backward compatibility is not an issue, then it is safe and
+	  recommended to say N here.
+
+	  For more information, see Documentation/filesystems/overlayfs.rst
+
+	  If unsure, say Y.
+
+config OVERLAY_FS_INDEX
+	bool "Overlayfs: turn on inodes index feature by default"
+	depends on OVERLAY_FS
+	help
+	  If this config option is enabled then overlay filesystems will use
+	  the index directory to map lower inodes to upper inodes by default.
+	  In this case it is still possible to turn off index globally with the
+	  "index=off" module option or on a filesystem instance basis with the
+	  "index=off" mount option.
+
+	  The inodes index feature prevents breaking of lower hardlinks on copy
+	  up.
+
+	  Note, that the inodes index feature is not backward compatible.
+	  That is, mounting an overlay which has an inodes index on a kernel
+	  that doesn't support this feature will have unexpected results.
+
+	  If unsure, say N.
+
+config OVERLAY_FS_NFS_EXPORT
+	bool "Overlayfs: turn on NFS export feature by default"
+	depends on OVERLAY_FS
+	depends on OVERLAY_FS_INDEX
+	depends on !OVERLAY_FS_METACOPY
+	help
+	  If this config option is enabled then overlay filesystems will use
+	  the index directory to decode overlay NFS file handles by default.
+	  In this case, it is still possible to turn off NFS export support
+	  globally with the "nfs_export=off" module option or on a filesystem
+	  instance basis with the "nfs_export=off" mount option.
+
+	  The NFS export feature creates an index on copy up of every file and
+	  directory.  This full index is used to detect overlay filesystems
+	  inconsistencies on lookup, like redirect from multiple upper dirs to
+	  the same lower dir.  The full index may incur some overhead on mount
+	  time, especially when verifying that directory file handles are not
+	  stale.
+
+	  Note, that the NFS export feature is not backward compatible.
+	  That is, mounting an overlay which has a full index on a kernel
+	  that doesn't support this feature will have unexpected results.
+
+	  Most users should say N here and enable this feature on a case-by-
+	  case basis with the "nfs_export=on" mount option.
+
+	  Say N unless you fully understand the consequences.
+
+config OVERLAY_FS_XINO_AUTO
+	bool "Overlayfs: auto enable inode number mapping"
+	default n
+	depends on OVERLAY_FS
+	depends on 64BIT
+	help
+	  If this config option is enabled then overlay filesystems will use
+	  unused high bits in underlying filesystem inode numbers to map all
+	  inodes to a unified address space.  The mapped 64bit inode numbers
+	  might not be compatible with applications that expect 32bit inodes.
+
+	  If compatibility with applications that expect 32bit inodes is not an
+	  issue, then it is safe and recommended to say Y here.
+
+	  For more information, see Documentation/filesystems/overlayfs.rst
+
+	  If unsure, say N.
+
+config OVERLAY_FS_METACOPY
+	bool "Overlayfs: turn on metadata only copy up feature by default"
+	depends on OVERLAY_FS
+	select OVERLAY_FS_REDIRECT_DIR
+	help
+	  If this config option is enabled then overlay filesystems will
+	  copy up only metadata where appropriate and data copy up will
+	  happen when a file is opened for WRITE operation. It is still
+	  possible to turn off this feature globally with the "metacopy=off"
+	  module option or on a filesystem instance basis with the
+	  "metacopy=off" mount option.
+
+	  Note, that this feature is not backward compatible.  That is,
+	  mounting an overlay which has metacopy only inodes on a kernel
+	  that doesn't support this feature will have unexpected results.
+
+	  If unsure, say N.
+
+config OVERLAY_FS_DEBUG
+	bool "Overlayfs: turn on extra debugging checks"
+	default n
+	depends on OVERLAY_FS
+	help
+	  Say Y here to enable extra debugging checks in overlayfs.
+
+	  If unsure, say N.