From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-64141: ksmbd: fix null pointer dereference in compare_guid_key()
Date: Sun, 19 Jul 2026 17:40:03 +0200 [thread overview]
Message-ID: <2026071929-CVE-2026-64141-2e37@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix null pointer dereference in compare_guid_key()
session_fd_check() walks the per-inode m_op_list during durable-handle
session teardown and sets op->conn = NULL for every opinfo whose conn
matched the closing session's connection. The matching opinfo, however,
stays linked in its per-ClientGuid lease_table_list entry's lb->lease_list
because destroy_lease_table() only runs on full TCP-connection teardown,
not on SESSION_LOGOFF.
If the same TCP connection then negotiates a fresh session with the
same ClientGuid (ClientGuid is bound to NEGOTIATE, not the session, and
is unchanged across LOGOFF + SETUP) and issues a SMB2 CREATE with a
lease context on a different inode, find_same_lease_key() walks
lb->lease_list, reaches the stale opinfo, and calls compare_guid_key(),
which unconditionally dereferences opinfo->conn->ClientGUID. The conn
pointer is NULL and the kernel panics.
Reproducer requires only a successful SMB2 SESSION_SETUP and a share
configured with 'durable handles = yes'. KASAN report on mainline
70390501d194:
general protection fault, probably for non-canonical address
0xdffffc0000000069: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000348-0x000000000000034f]
Workqueue: ksmbd-io handle_ksmbd_work
RIP: 0010:bcmp+0x5b/0x230
Call Trace:
compare_guid_key+0x4b/0xd0
find_same_lease_key+0x324/0x690
smb2_open+0x6aea/0x8e60
handle_ksmbd_work+0x796/0xee0
...
Faulting address 0x348 is the offset of ClientGUID within struct
ksmbd_conn, confirming opinfo->conn was NULL.
Read opinfo->conn once and bail out if it has been cleared by a
concurrent session_fd_check(). A half-detached opinfo cannot be the
owner of an active lease, so returning 0 is the correct match result.
The Linux kernel CVE team has assigned CVE-2026-64141 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.6.32 with commit 8df4bcdb0a4232192b2445256c39b787d58ef14d and fixed in 6.6.142 with commit e43cb36d4d7827710cfcd48e95e29a507f0d87be
Issue introduced in 6.9 with commit c8efcc786146a951091588e5fa7e3c754850cb3c and fixed in 6.12.92 with commit 0836081b394ca074d1b910f2b990ff7b4b4404c7
Issue introduced in 6.9 with commit c8efcc786146a951091588e5fa7e3c754850cb3c and fixed in 6.18.34 with commit cd5c1b75d2f454f625d7dc55bd3ae21d0855f6ad
Issue introduced in 6.9 with commit c8efcc786146a951091588e5fa7e3c754850cb3c and fixed in 7.0.11 with commit af86896ca3239e25a6bd7d352213371265073d38
Issue introduced in 6.9 with commit c8efcc786146a951091588e5fa7e3c754850cb3c and fixed in 7.1 with commit 4b83cbc4c15f09b000cc06f033f64b0824b6dc87
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-2026-64141
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/server/oplock.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/e43cb36d4d7827710cfcd48e95e29a507f0d87be
https://git.kernel.org/stable/c/0836081b394ca074d1b910f2b990ff7b4b4404c7
https://git.kernel.org/stable/c/cd5c1b75d2f454f625d7dc55bd3ae21d0855f6ad
https://git.kernel.org/stable/c/af86896ca3239e25a6bd7d352213371265073d38
https://git.kernel.org/stable/c/4b83cbc4c15f09b000cc06f033f64b0824b6dc87
reply other threads:[~2026-07-19 15:45 UTC|newest]
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