CVE-2026-64383: smb: client: fix double-free in SMB2_flush() replay

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

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

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

smb: client: fix double-free in SMB2_flush() replay

SMB2_flush() keeps its response buffer bookkeeping across replay
attempts. If a replayable flush response is received and the retry then
fails before cifs_send_recv() stores a replacement response, flush_exit
will free the stale response pointer a second time.

Reinitialize resp_buftype and rsp_iov at the top of the replay loop so
cleanup only acts on response state produced by the current attempt.
This fixes a double-free without changing replay handling for successful
requests.

The Linux kernel CVE team has assigned CVE-2026-64383 to this issue.


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

	Issue introduced in 6.6.32 with commit 433042a91f9373241307725b52de573933ffedbf and fixed in 6.6.145 with commit 6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb
	Issue introduced in 6.8 with commit 4f1fffa2376922f3d1d506e49c0fd445b023a28e and fixed in 6.12.96 with commit 878757163eea684750107a31ea134c103863515d
	Issue introduced in 6.8 with commit 4f1fffa2376922f3d1d506e49c0fd445b023a28e and fixed in 6.18.39 with commit 3407240cde132a4b72d6429a2625a09a2f78adaf
	Issue introduced in 6.8 with commit 4f1fffa2376922f3d1d506e49c0fd445b023a28e and fixed in 7.1.4 with commit 013a9a3da46c5dabcf18f65ea6a47874ba12a15d
	Issue introduced in 6.8 with commit 4f1fffa2376922f3d1d506e49c0fd445b023a28e and fixed in 7.2-rc1 with commit 4be31c943a3a27a5a0251dbb8f5cb89059ec3d5a

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-2026-64383
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:
	fs/smb/client/smb2pdu.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/6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb
	https://git.kernel.org/stable/c/878757163eea684750107a31ea134c103863515d
	https://git.kernel.org/stable/c/3407240cde132a4b72d6429a2625a09a2f78adaf
	https://git.kernel.org/stable/c/013a9a3da46c5dabcf18f65ea6a47874ba12a15d
	https://git.kernel.org/stable/c/4be31c943a3a27a5a0251dbb8f5cb89059ec3d5a