In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_sock: Serialize dead-device detachment
Rebinding an HCI socket after its controller is unregistered can race
monitor control replay and crash the kernel. hci_sock_bind() clears
hci_pi(sk)->hdev and drops the device reference under only the socket
lock, whereas send_monitor_control_replay() holds hci_sk_list.lock for
reading.
Replay can observe a non-NULL hdev, then bind can clear it and drop the
last reference before create_monitor_ctrl_open() reads hdev->id. This
can cause a NULL pointer dereference if the pointer is reloaded, or a
use-after-free if the old
Bluetooth: RFCOMM: free the skb when the DLC has no owner
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: RFCOMM: free the skb when the DLC has no owner
rfcomm_recv_data() hands the skb to d->data_ready() and returns 0
without freeing it, so the callback owns the skb from that point on.
The tty implementation frees it when the DLC has been detached from its
device:
static void rfcomm_dev_data_ready(struct rfcomm_dlc *dlc,
struct sk_buff *skb)
{
struct rfcomm_dev *dev = dlc->owner;
if (!dev) {
kfree_skb(skb);
return;
}
The socket implementation returns without
Bluetooth: RFCOMM: Fix NULL tty_dev dereference in rfcomm_dev_shutdown
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: RFCOMM: Fix NULL tty_dev dereference in rfcomm_dev_shutdown
syzbot hit a NULL pointer dereference in rfcomm_dev_shutdown() when an
RFCOMM tty is closed.
rfcomm_dev_add() puts the new device on rfcomm_dev_list first and only
then registers the tty device and saves it in dev->tty_dev. If that
registration fails, dev->tty_dev is never set at all. The device can be
looked up in the meantime, so an open() of /dev/rfcommN gets through
rfcomm_tty_install() and attaches to it. When that tty is closed again,
rfcomm_dev_shutdown() uses dev->tty_dev without checking it:
drm/fb-helper: defer setup when fbdev_probe() fails, not just on -EAGAIN
In the Linux kernel, the following vulnerability has been resolved:
drm/fb-helper: defer setup when fbdev_probe() fails, not just on -EAGAIN
__drm_fb_helper_initial_config_and_unlock() calls
drm_client_modeset_probe() first, which already fills in each
mode_set->mode/num_connectors for every connected output, and only
afterwards calls drm_fb_helper_single_fb_probe() to create
fb_helper->fb and wire it into those mode_sets via
drm_setup_crtcs_fb().
If drm_fb_helper_single_fb_probe() fails with anything other than
-EAGAIN (e.g. dev->driver->fbdev_probe() itself fails), the function
bails out before drm_setup_crtcs_fb() runs and before settin
In the Linux kernel, the following vulnerability has been resolved:
drm/vmwgfx: validate pitch coming from userspace
Validate the pitch, alongside the box dimensions before trying
to copy data from the underlying surface. Fixes possible
out of bounds reads with cursor snooping.
In the Linux kernel, the following vulnerability has been resolved:
fs: don't silently unmount busy mounts
The propagate_mount_busy() helper exists to decide whether a synchronous
can suceed. It does that by looking at the copies of the victims in the
mounts its parent propagates to. One of those functions from propagation
hell.
It skips a copy that has child mounts except for the case of a single
child mount covering the copy's root. That algorithm used to be exact.
It isn't anymore.
Originally only childless copies were unmounted during propagation.
And 1064f874abc0 ("mnt: Tuck mounts under others instead of creating
shadow/side mounts.
namespace: don't inherit MNT_UMOUNT in clone_mnt()
In the Linux kernel, the following vulnerability has been resolved:
namespace: don't inherit MNT_UMOUNT in clone_mnt()
MNT_UMOUNT gets raised on a mount that umount_tree() or umount_one() has
taken out of its namespace. It's never cleared. __detach_mounts()
unhooks a mount that carries it instead of unmounting it.
disconnect_mount() lets an unmounted child stay attached only if its
parent carries it. propagate_umount() takes it as the sign that a mount
is going to be unmounted when it decides what else can be unmounted,
where a chain of locked mounts ends and where a for reparenting an
overmount.
clone_mnt() copies the flags of the source
In the Linux kernel, the following vulnerability has been resolved:
namespace: don't copy an unmounted mount tree
may_copy_tree() accepts a mount whose root is an nsfs or pidfs file
before it checks whether that mount is mounted. This exception exists
for nsfs and pidfs mounts. They are part of no mount namespace so
neither check_mnt() nor is_mounted() would let them through and
bind-mounting a nsfsfd or a pidfd wouldn't work.
Problem is that exception also admits a bind mount of such a file when
it was lazily unmounted and is only kept alive by a file descriptor:
mount --bind /proc/self/ns/net /tmp/x
exec 3< /tmp/x
umount -l /tmp/x
namespace: check a submount for references right before unmounting it
In the Linux kernel, the following vulnerability has been resolved:
namespace: check a submount for references right before unmounting it
shrink_submounts() and mark_mounts_for_expiry() first collect all the
mounts they are allowed to unmount and then unmount them.
Whether a mount is busy is decided by propagate_mount_busy() on the
tree. But unmounting the first mount changes the tree that the second
one propagates into. propagate_umount()
moves a surviving overmount off a copy it unmounts and mounts it where
the copy was mounted. If that's where the propagated copy of the second
victim is looked up the overmount becomes a candidate of the
namespace: check a recursive bind mount for mount namespace loops
In the Linux kernel, the following vulnerability has been resolved:
namespace: check a recursive bind mount for mount namespace loops
do_loopback() refuses to bind mount the file of a mount namespace that
is as old as the caller's or older because a mount namespace that holds
a mount of its own file, or of an ancestor's, would cause a cycle. But
it only checks the dentry the bind mount starts from. With MS_REC
everything below it is copied and do_loopback() passes
CL_COPY_MNT_NS_FILE so mount namespace files below the source are
copied.
That's fine for a source in the caller's own mount namespace. Every
mount namespace file in there passed
namespace: check the mounts before reading their parents in pivot_root()
In the Linux kernel, the following vulnerability has been resolved:
namespace: check the mounts before reading their parents in pivot_root()
path_pivot_root() reads the parents of new_root and of the caller's root
and checks whether they are shared before it checks that either mount is
in the caller's mount namespace. Only namespace_sem is held. That's fine
for a mount that is in the caller's mount namespace.
But new_root can be a file descriptor to a mount that has been unmounted
and that only the file descriptor keeps alive. If that mount stayed
attached to its parent when it was unmounted nothing pins the parent for
it. The final mntput
dcache: don't put a mountpoint on a dentry that's being removed
In the Linux kernel, the following vulnerability has been resolved:
dcache: don't put a mountpoint on a dentry that's being removed
rmdir(), unlink() and rename() call dont_mount() on the victim and then
detach_mounts() with the victim's inode locked. do_lock_mount() takes
the inode lock of the mountpoint and checks cant_mount() so a mount
can't show up after detach_mounts().
But attach_recursive_mnt() makes a second mountpoint for the root of the
source mount so that the mounts already located at the destination can
be put on top of it. No inode is locked for that one and d_set_mounted()
only refuses a dentry that is unlinked. Between det
namespace: unhash a dentry before detaching the mounts on it
In the Linux kernel, the following vulnerability has been resolved:
namespace: unhash a dentry before detaching the mounts on it
unlink(), rmdir() and rename() remove the entry from the filesystem,
call detach_mounts() on the entry with the inode locked and then call
d_delete() once the inode is unlocked.
The thing is that between detach_mounts() and d_delete() the dentry is
still hashed and positive. But after detach_mounts() nothing covers the
dentry anymore. A lookup that finds this dentry in the dcache can
uncover what the mounts hid.
That's a problem when unlinking files or directories that are
mountpoints in other mount namespaces.
namei: don't reveal overmounted entries in refwalk
In the Linux kernel, the following vulnerability has been resolved:
namei: don't reveal overmounted entries in refwalk
In rcuwalk the dentry is validated before it is accepted. step_into()
step_into() rechecks d_seq and __follow_mount_rcu() rechecks mount_lock.
An entry that gets unlinked in between causes the lookup to retry and
miss.
A refwalk doesn't do this. lookup_fast() takes a reference on the hashed
dentry and simply accepts it. So an unlink that happens after the
reference was taken isn't seen by refwalk. That's fine for a simple
file. We just happened to open it before it was unlinked, no problem.
For a mountpoint and specifical
In the Linux kernel, the following vulnerability has been resolved:
namespace: never expire a locked mount
Locked mounts are special. They protect the underlying files and
directories from being revealed. do_umount() refuses to unmount locked
mounts but shrink_submounts() doesn't.
A shrinkable mount can become locked once the owner of a user namespace
puts it beneath a locked mount with MOVE_MOUNT_BENEATH. The locked
property now moves to the mount at the bottom making it possible to
unmount the top mount.
So umount() of an unlocked ancestor now expires the bottom mount first
and the covered directory is revealed:
move_mount(c -> x/hid
namespace: handle mount locking for automounts correctly
In the Linux kernel, the following vulnerability has been resolved:
namespace: handle mount locking for automounts correctly
If mounts are propagated across user namespaces, attach_recursive_mnt()
locks every copy of the source mount to protect overmounts from
vanishing and revealing the underlying files or directories.
The user namespace is taken from the caller's mount namespaces since
this is where the mounts end up. Except, that's not always true.
Automounts may legitimately get popped in by tasks located in a
different mount and user namespace during path lookup.
Then check doesn't make sense at that point. The copy in the namespace
xfs: stop exchanging reflink flags when exchanging mappings
In the Linux kernel, the following vulnerability has been resolved:
xfs: stop exchanging reflink flags when exchanging mappings
When an exchange covers both files from offset 0 to i_disk_size,
xmi_can_exchange_reflink_flags() assumes every mapping moved and hands
the reflink flag over to the other file.
That assumption is wrong. A file can still own shared blocks past
i_disk_size, e.g. after EXCHANGE_RANGE_TO_EOF sets a smaller size
without unmapping anything. The flag is cleared anyway, and the next
write to such a block happens in place instead of CoW, corrupting the
other file that shares it.
Commit a23eca88448e ("xfs: fix exchange-r
cgroup/cpuset: Don't access cpuset_cgrp_subsys.root in is_in_v2_mode()
In the Linux kernel, the following vulnerability has been resolved:
cgroup/cpuset: Don't access cpuset_cgrp_subsys.root in is_in_v2_mode()
After seeing the patch [1] to guard is_in_v2_mode() with RCU, it makes
me realize that is_in_v2_mode() may be called in a context where a new
cgroup filesystem is being rebound with stale cpuset_cgrp_subsys.root
pointer. Avoid this potential UaF situation by adding a new cpuset_v2_mode
flag which is set when the cpuset_v2_mode mount option is used. This
flag is written into only when cpuset_bind() is being called with a
stable cpuset_cgrp_subsys.root value. The is_in_v2_mode() helper is
modified to read
In the Linux kernel, the following vulnerability has been resolved:
drm/vc4: Free the BO cache size list on teardown
vc4_bo_cache_destroy() purges the cached BOs but never frees the size
list, leaking it on every unbind.
net/sched: em_text: reject unterminated algo before autoload
In the Linux kernel, the following vulnerability has been resolved:
net/sched: em_text: reject unterminated algo before autoload
This is a follow-up to commit 9c572a83037a ("net/sched: fix potential
stack infoleak in em_text_dump()"), which zero-initialised the dump-side
struct. Sashiko pointed at a pre-existing bug that exposed the change-side
input-validation gap open.
em_text_change() casts the raw netlink attribute payload to struct
tcf_em_text and passes conf->algo, a 16-byte array with no enforced NUL
terminator, to textsearch_prepare(). On the TS_AUTOLOAD retry
textsearch_prepare() calls request_module("ts_%s", algo); vsnprintf()
w