Subject: CVE-2024-36962: net: ks8851: Queue RX packets in IRQ handler instead of disabling BHs

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

net: ks8851: Queue RX packets in IRQ handler instead of disabling BHs

Currently the driver uses local_bh_disable()/local_bh_enable() in its
IRQ handler to avoid triggering net_rx_action() softirq on exit from
netif_rx(). The net_rx_action() could trigger this driver .start_xmit
callback, which is protected by the same lock as the IRQ handler, so
calling the .start_xmit from netif_rx() from the IRQ handler critical
section protected by the lock could lead to an attempt to claim the
already claimed lock, and a hang.

The local_bh_disable()/local_bh_enable() approach works only in case
the IRQ handler is protected by a spinlock, but does not work if the
IRQ handler is protected by mutex, i.e. this works for KS8851 with
Parallel bus interface, but not for KS8851 with SPI bus interface.

Remove the BH manipulation and instead of calling netif_rx() inside
the IRQ handler code protected by the lock, queue all the received
SKBs in the IRQ handler into a queue first, and once the IRQ handler
exits the critical section protected by the lock, dequeue all the
queued SKBs and push them all into netif_rx(). At this point, it is
safe to trigger the net_rx_action() softirq, since the netif_rx()
call is outside of the lock that protects the IRQ handler.

The Linux kernel CVE team has assigned CVE-2024-36962 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 6.1.87 with commit 492337a4fbd1 and fixed in 6.1.91 with commit 8a3ff43dcbab
	Issue introduced in 6.6.28 with commit cba376eb036c and fixed in 6.6.31 with commit ae87f661f3c1
	Issue introduced in 6.8.7 with commit 49d5d70538b6 and fixed in 6.8.10 with commit 7e2901a2a919

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-36962
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/net/ethernet/micrel/ks8851_common.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/8a3ff43dcbab7c96f9e8cf2bd1049ab8d6e59545
	https://git.kernel.org/stable/c/ae87f661f3c1a3134a7ed86ab69bf9f12af88993
	https://git.kernel.org/stable/c/7e2901a2a9195da76111f351584bf77552a038f0
	https://git.kernel.org/stable/c/e0863634bf9f7cf36291ebb5bfa2d16632f79c49