[PATCH OLK-5.10] ksmbd: defer destroy_previous_session() until after NTLM authentication
mainline inclusion from mainline-v7.2-rc5 commit c74801ee524f477c174a1899782b6c3b6918d407 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16939 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- In ntlm_authenticate(), destroy_previous_session() is called using a user pointer resolved from the client-supplied NTLM blob username field before the NTLMv2 response is validated. An authenticated attacker can set the NTLM blob username to match a victim account and set PreviousSessionId to the victim's session ID; destroy_previous_session() destroys the victim's session while ksmbd_decode_ntlmssp_auth_blob() subsequently rejects the request with -EPERM. Move destroy_previous_session() and the prev_id assignment to after ksmbd_decode_ntlmssp_auth_blob() returns success and use sess->user rather than the pre-authentication lookup result. This matches the ordering already used by krb5_authenticate(), where destroy_previous_session() is called only after ksmbd_krb5_authenticate() returns success. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/linux-cifs/20260702155449.3639773-1-james_montgomery... Signed-off-by: James Montgomery <james_montgomery@disroot.org> Acked-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com> Conflicts: fs/ksmbd/smb2pdu.c [ctx conflicts] Signed-off-by: Lai Zewei <laizewei3@huawei.com> --- fs/ksmbd/smb2pdu.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c index ff3bcd2f7c46..d8262429e31b 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -1487,11 +1487,6 @@ static int ntlm_authenticate(struct ksmbd_work *work, return -EPERM; } - /* Check for previous session */ - prev_id = le64_to_cpu(req->PreviousSessionId); - if (prev_id && prev_id != sess->id) - destroy_previous_session(conn, user, prev_id); - if (sess->state == SMB2_SESSION_VALID) { /* * Reuse session if anonymous try to connect @@ -1526,6 +1521,10 @@ static int ntlm_authenticate(struct ksmbd_work *work, } } + prev_id = le64_to_cpu(req->PreviousSessionId); + if (prev_id && prev_id != sess->id) + destroy_previous_session(conn, sess->user, prev_id); + /* * If session state is SMB2_SESSION_VALID, We can assume * that it is reauthentication. And the user/password -- 2.52.0
mainline inclusion from mainline-v7.2-rc4 commit 15b38176fd1530372905c602fde51fe89ec8c877 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16881 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- When ksmbd validates a compound (chained) SMB2 request, ksmbd_smb2_check_message() reads pdu->StructureSize2 without first checking that the compound element is large enough to contain it. StructureSize2 is a 2-byte field at offset 64 (__SMB2_HEADER_STRUCTURE_SIZE) from the start of each element. The compound-walking logic only guarantees that a full 64-byte SMB2 header is present for the trailing element: when NextCommand is 0, len is reduced to the number of bytes remaining after next_smb2_rcv_hdr_off. A remote client can craft a compound request whose last element has exactly 64 bytes, so the 2-byte StructureSize2 read at offset 64 extends one byte past the receive buffer, producing a slab-out-of-bounds read. BUG: KASAN: slab-out-of-bounds in ksmbd_smb2_check_message (fs/smb/server/smb2misc.c:402) Read of size 2 at addr ffff888012ae31ac by task kworker/0:1/14 The buggy address is located 172 bytes inside of allocated 173-byte region Workqueue: ksmbd-io handle_ksmbd_work Call Trace: ... kasan_report (mm/kasan/report.c:595) ksmbd_smb2_check_message (fs/smb/server/smb2misc.c:402) handle_ksmbd_work (fs/smb/server/server.c:119) process_one_work (kernel/workqueue.c:3314) worker_thread (kernel/workqueue.c:3397) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) ret_from_fork_asm (arch/x86/entry/entry_64.S:245) Reject any compound element that is too small to hold StructureSize2 before dereferencing it. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Reported-by: AutonomousCodeSecurity@microsoft.com Signed-off-by: Xiang Mei (Microsoft) <xmei5@asu.edu> Acked-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Lai Zewei <laizewei3@huawei.com> --- fs/ksmbd/smb2misc.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/ksmbd/smb2misc.c b/fs/ksmbd/smb2misc.c index c460d2bd4133..162687430e10 100644 --- a/fs/ksmbd/smb2misc.c +++ b/fs/ksmbd/smb2misc.c @@ -405,6 +405,11 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work) return 1; } + if (len < __SMB2_HEADER_STRUCTURE_SIZE + sizeof(__le16)) { + ksmbd_debug(SMB, "Message is too small for StructureSize2\n"); + return 1; + } + if (smb2_req_struct_sizes[command] != pdu->StructureSize2) { if (!(command == SMB2_OPLOCK_BREAK_HE && (le16_to_cpu(pdu->StructureSize2) == OP_BREAK_STRUCT_SIZE_20 || -- 2.52.0
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