Steve French reported null pointer dereference error from sha256 lib.
cifs.ko can send session setup requests on reused connection.
If reused connection is used for binding session, conn->binding can
still remain true and generate_preauth_hash() will not set
sess->Preauth_HashValue and it will be NULL.
It is used as a material to create an encryption key in
ksmbd_gen_smb311_encryptionkey. ->Preauth_HashValue cause null pointer
dereference error from crypto_shash_update().
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 8 PID: 429254 Comm: kworker/8:39
Hardware name: LENOVO 20MAS08500/20MAS08500, BIOS N2CET69W (1.52 )
Workqueue: ksmbd-io handle_ksmbd_work [ksmbd]
RIP: 0010:lib_sha256_base_do_update.isra.0+0x11e/0x1d0 [sha256_ssse3]
<TASK>
? show_regs+0x6d/0x80
? __die+0x24/0x80
? page_fault_oops+0x99/0x1b0
? do_user_addr_fault+0x2ee/0x6b0
? exc_page_fault+0x83/0x1b0
? asm_exc_page_fault+0x27/0x30
? __pfx_sha256_transform_rorx+0x10/0x10 [sha256_ssse3]
? lib_sha256_base_do_update.isra.0+0x11e/0x1d0 [sha256_ssse3]
? __pfx_sha256_transform_rorx+0x10/0x10 [sha256_ssse3]
? __pfx_sha256_transform_rorx+0x10/0x10 [sha256_ssse3]
_sha256_update+0x77/0xa0 [sha256_ssse3]
sha256_avx2_update+0x15/0x30 [sha256_ssse3]
crypto_shash_update+0x1e/0x40
hmac_update+0x12/0x20
crypto_shash_update+0x1e/0x40
generate_key+0x234/0x380 [ksmbd]
generate_smb3encryptionkey+0x40/0x1c0 [ksmbd]
ksmbd_gen_smb311_encryptionkey+0x72/0xa0 [ksmbd]
ntlm_authenticate.isra.0+0x423/0x5d0 [ksmbd]
smb2_sess_setup+0x952/0xaa0 [ksmbd]
__process_request+0xa3/0x1d0 [ksmbd]
__handle_ksmbd_work+0x1c4/0x2f0 [ksmbd]
handle_ksmbd_work+0x2d/0xa0 [ksmbd]
process_one_work+0x16c/0x350
worker_thread+0x306/0x440
? __pfx_worker_thread+0x10/0x10
kthread+0xef/0x120
? __pfx_kthread+0x10/0x10
ret_from_fork+0x44/0x70
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1b/0x30
</TASK>
Fixes: f5a544e3bab7 ("ksmbd: add support for SMB3 multichannel")
Cc: stable@xxxxxxxxxxxxxxx # v5.15+
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 20846a4d3031..8bdc59251418 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -1690,6 +1690,8 @@ int smb2_sess_setup(struct ksmbd_work *work)
rc = ksmbd_session_register(conn, sess);
if (rc)
goto out_err;
+
+ conn->binding = false;
} else if (conn->dialect >= SMB30_PROT_ID &&
(server_conf.flags & KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL) &&
req->Flags & SMB2_SESSION_REQ_FLAG_BINDING) {
@@ -1768,6 +1770,8 @@ int smb2_sess_setup(struct ksmbd_work *work)
sess = NULL;
goto out_err;
}
+
+ conn->binding = false;
}
work->sess = sess;
