CVE-2026-74626: NTB: ntb_netdev: Preserve RX queue depth on allocation failure

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

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

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

NTB: ntb_netdev: Preserve RX queue depth on allocation failure

ntb_netdev_rx_handler() hands the received skb to the network stack
before allocating its replacement. If the allocation fails, nothing is
reposted. Every failure therefore takes one buffer out of the RX queue
while the interface remains up, and enough failures eventually stall
reception.

A retry path could refill the queue later, but ntb_netdev has none.
Allocate the replacement first instead. If that fails, drop the packet
and repost the same skb. This keeps the queue full and lets packet
delivery resume as soon as memory is available again.

The Linux kernel CVE team has assigned CVE-2026-74626 to this issue.


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

	Issue introduced in 3.9 with commit 548c237c0a9972df5d1afaca38aa733ee577128d and fixed in 7.1.9 with commit 755fd7843f300d724caceabdf9bb13adc8701540
	Issue introduced in 3.9 with commit 548c237c0a9972df5d1afaca38aa733ee577128d and fixed in 7.2 with commit d2121faf133ac3bf9531b53a7e21273649a08517

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-2026-74626
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/ntb_netdev.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/755fd7843f300d724caceabdf9bb13adc8701540
	https://git.kernel.org/stable/c/d2121faf133ac3bf9531b53a7e21273649a08517