CVE-2026-74429: rxrpc: Fix the reception of a reply packet before data transmission

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

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

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

rxrpc: Fix the reception of a reply packet before data transmission

Fix rxrpc_receiving_reply() to handle the reception of an apparent reply
DATA packet before rxrpc has had a chance to send any request DATA packets
on a client call by checking to see if the call has been exposed yet by
sending the first packet.

Without this, rxrpc_rotate_tx_window() might oops.

Also fix rxrpc_rotate_tx_window() to handle the Tx queue being empty by
changing the do...while loop into a while loop, just in case a call is
abnormally terminated by an early reply before the last request packet is
transmitted.

The Linux kernel CVE team has assigned CVE-2026-74429 to this issue.


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

	Issue introduced in 6.14 with commit b341a0263b1b804d329f864c2dc24815364510ec and fixed in 6.18.40 with commit f9be514984471ff0003738b2e1efed12bc3433ff
	Issue introduced in 6.14 with commit b341a0263b1b804d329f864c2dc24815364510ec and fixed in 7.1.5 with commit e220ae559e5a0fc33e41ec6a348ea50387cb8b0f
	Issue introduced in 6.14 with commit b341a0263b1b804d329f864c2dc24815364510ec and fixed in 7.2-rc1 with commit a58e33405acd2584e730c1da72635f822ada6b49

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-2026-74429
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:
	net/rxrpc/input.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/f9be514984471ff0003738b2e1efed12bc3433ff
	https://git.kernel.org/stable/c/e220ae559e5a0fc33e41ec6a348ea50387cb8b0f
	https://git.kernel.org/stable/c/a58e33405acd2584e730c1da72635f822ada6b49