Archivos de la categoría: Seguridad

mmc: davinci: Don't strip remove function when driver is builtin

Using __exit for the remove function results in the remove callback being
discarded with CONFIG_MMC_DAVINCI=y. When such a device gets unbound (e.g.
using sysfs or hotplug), the driver is just removed without the cleanup
being performed. This results in resource leaks. Fix it by compiling in the
remove callback unconditionally.

This also fixes a W=1 modpost warning:

WARNING: modpost: drivers/mmc/host/davinci_mmc: section mismatch in
reference: davinci_mmcsd_driver+0x10 (section: .data) ->
davinci_mmcsd_remove (section: .exit.text)

bcache: fix variable length array abuse in btree_iter

btree_iter is used in two ways: either allocated on the stack with a
fixed size MAX_BSETS, or from a mempool with a dynamic size based on the
specific cache set. Previously, the struct had a fixed-length array of
size MAX_BSETS which was indexed out-of-bounds for the dynamically-sized
iterators, which causes UBSAN to complain.

This patch uses the same approach as in bcachefs's sort_iter and splits
the iterator into a btree_iter with a flexible array member and a
btree_iter_stack which embeds a btree_iter as well as a fixed-length
data array.

media: v4l: async: Properly re-initialise notifier entry in unregister

The notifier_entry of a notifier is not re-initialised after unregistering
the notifier. This leads to dangling pointers being left there so use
list_del_init() to return the notifier_entry an empty list.

KVM: SVM: WARN on vNMI + NMI window iff NMIs are outright masked

When requesting an NMI window, WARN on vNMI support being enabled if and
only if NMIs are actually masked, i.e. if the vCPU is already handling an
NMI. KVM's ABI for NMIs that arrive simultanesouly (from KVM's point of
view) is to inject one NMI and pend the other. When using vNMI, KVM pends
the second NMI simply by setting V_NMI_PENDING, and lets the CPU do the
rest (hardware automatically sets V_NMI_BLOCKING when an NMI is injected).

However, if KVM can't immediately inject an NMI, e.g. because the vCPU is
in an STI shadow or is running with GIF=0, then KVM will request an NMI
window and trigger the WARN (but still function correctly).

Whether or not the GIF=0 case makes sense is debatable, as the intent of
KVM's behavior is to provide functionality that is as close to real
hardware as possible. E.g. if two NMIs are sent in quick succession, the
probability of both NMIs arriving in an STI shadow is infinitesimally low
on real hardware, but significantly larger in a virtual environment, e.g.
if the vCPU is preempted in the STI shadow. For GIF=0, the argument isn't
as clear cut, because the window where two NMIs can collide is much larger
in bare metal (though still small).

That said, KVM should not have divergent behavior for the GIF=0 case based
on whether or not vNMI support is enabled. And KVM has allowed
simultaneous NMIs with GIF=0 for over a decade, since commit 7460fb4a3400
("KVM: Fix simultaneous NMIs"). I.e. KVM's GIF=0 handling shouldn't be
modified without a *really* good reason to do so, and if KVM's behavior
were to be modified, it should be done irrespective of vNMI support.