CVE-2026-31710: smb: client: fix dir separator in SMB1 UNIX mounts

CVE-2026-31710: smb: client: fix dir separator in SMB1 UNIX mounts

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

smb: client: fix dir separator in SMB1 UNIX mounts

When calling cifs_mount_get_tcon() with SMB1 UNIX mounts,
@cifs_sb->mnt_cifs_flags needs to be read or updated only after
calling reset_cifs_unix_caps(), otherwise it might end up with missing
CIFS_MOUNT_POSIXACL and CIFS_MOUNT_POSIX_PATHS bits.

This fixes the wrong dir separator used in paths caused by the missing
CIFS_MOUNT_POSIX_PATHS bit in cifs_sb_info::mnt_cifs_flags.

The Linux kernel CVE team has assigned CVE-2026-31710 to this issue.


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

	Issue introduced in 7.0 with commit 4fc3a433c13944ee5766ec5b9bf6f1eb4d29b880 and fixed in 7.0.2 with commit fbbfcf35e1ee3396631f3dc6214cb626aa9814c3
	Issue introduced in 7.0 with commit 4fc3a433c13944ee5766ec5b9bf6f1eb4d29b880 and fixed in 7.1-rc1 with commit c4d3fc5844d685441befd0caaab648321013cdfd

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-2026-31710
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/connect.c
	fs/smb/client/smb1ops.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/fbbfcf35e1ee3396631f3dc6214cb626aa9814c3
	https://git.kernel.org/stable/c/c4d3fc5844d685441befd0caaab648321013cdfd