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.
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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
||||||||||||||||||||||||
| Linux | Linux | affected |
|
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Fixes
Solution
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Workaround
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References
History
Sun, 19 Jul 2026 16:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | ksmbd: fix null pointer dereference in compare_guid_key() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-07-19T15:40:33.890Z
Reserved: 2026-07-19T07:54:57.037Z
Link: CVE-2026-64141
Vulnrichment
No data.
NVD
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Redhat
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OpenCVE Enrichment
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Weaknesses
No weakness.