GHSA-HXMM-JMJ9-253J
Vulnerability from github – Published: 2026-06-25 09:31 – Updated: 2026-07-08 06:31In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers
smb2_oplock_break_noti() and smb2_lease_break_noti() read opinfo->conn into a local with neither READ_ONCE() nor a NULL check. Both run from oplock_break() after opinfo_get_list() has dropped ci->m_lock, so a concurrent SMB2 LOGOFF (session_fd_check()) can set op->conn = NULL under ci->m_lock within that window. ksmbd_conn_r_count_inc(conn) then writes through NULL at offset 0xc4 -- a remotely triggerable oops.
Guard both reads the way compare_guid_key() already does: read opinfo->conn with READ_ONCE() and return early if it is NULL, before allocating the work struct so nothing leaks. A NULL conn means the client is gone and the break is moot, so return 0; oplock_break() treats that as success and runs the normal teardown.
{
"affected": [],
"aliases": [
"CVE-2026-53271"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-06-25T09:16:45Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix NULL-deref of opinfo-\u003econn in oplock/lease break notifiers\n\nsmb2_oplock_break_noti() and smb2_lease_break_noti() read opinfo-\u003econn\ninto a local with neither READ_ONCE() nor a NULL check. Both run from\noplock_break() after opinfo_get_list() has dropped ci-\u003em_lock, so a\nconcurrent SMB2 LOGOFF (session_fd_check()) can set op-\u003econn = NULL\nunder ci-\u003em_lock within that window. ksmbd_conn_r_count_inc(conn) then\nwrites through NULL at offset 0xc4 -- a remotely triggerable oops.\n\nGuard both reads the way compare_guid_key() already does: read\nopinfo-\u003econn with READ_ONCE() and return early if it is NULL, before\nallocating the work struct so nothing leaks. A NULL conn means the\nclient is gone and the break is moot, so return 0; oplock_break() treats\nthat as success and runs the normal teardown.",
"id": "GHSA-hxmm-jmj9-253j",
"modified": "2026-07-08T06:31:34Z",
"published": "2026-06-25T09:31:23Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53271"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1ff58dcfcab434ebb51649da33774fbb8e1f7b67"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/75e33deda658c1ab3a9336cbdb1436536f9b3660"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/945a86b21b40fb17183f5b27461baa6f03e2467f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b003086d76968298f22e7cf62239833b5a3a06b1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e735dbd489e3ea02be78dba991056fe1138be51e"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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