kernel/linux.git/fs/smb/client, branch v6.1.168

smb: client: Compare MACs in constant time

2026-03-25T10:03:18+00:00

commit 26bc83b88bbbf054f0980a4a42047a8d1e210e4c upstream. To prevent timing attacks, MAC comparisons need to be constant-time. Replace the memcmp() with the correct function, crypto_memneq(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Acked-by: Paulo Alcantara (Red Hat) Signed-off-by: Eric Biggers Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

cifs: open files should not hold ref on superblock

2026-03-25T10:03:16+00:00

[ Upstream commit 340cea84f691c5206561bb2e0147158fe02070be ] Today whenever we deal with a file, in addition to holding a reference on the dentry, we also get a reference on the superblock. This happens in two cases: 1. when a new cinode is allocated 2. when an oplock break is being processed The reasoning for holding the superblock ref was to make sure that when umount happens, if there are users of inodes and dentries, it does not try to clean them up and wait for the last ref to superblock to be dropped by last of such users. But the side effect of doing that is that umount silently drops a ref on the superblock and we could have deferred closes and lease breaks still holding these refs. Ideally, we should ensure that all of these users of inodes and dentries are cleaned up at the time of umount, which is what this code is doing. This code change allows these code paths to use a ref on the dentry (and hence the inode). That way, umount is ensured to clean up SMB client resources when it's the last ref on the superblock (For ex: when same objects are shared). The code change also moves the call to close all the files in deferred close list to the umount code path. It also waits for oplock_break workers to be flushed before calling kill_anon_super (which eventually frees up those objects). Fixes: 24261fc23db9 ("cifs: delay super block destruction until all cifsFileInfo objects are gone") Fixes: 705c79101ccf ("smb: client: fix use-after-free in cifs_oplock_break") Cc: Signed-off-by: Shyam Prasad N Signed-off-by: Steve French [ kmalloc_obj() => kmalloc(), remove trace_smb3_tcon_ref() ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb: client: fix krb5 mount with username option

2026-03-25T10:03:12+00:00

commit 12b4c5d98cd7ca46d5035a57bcd995df614c14e1 upstream. Customer reported that some of their krb5 mounts were failing against a single server as the client was trying to mount the shares with wrong credentials. It turned out the client was reusing SMB session from first mount to try mounting the other shares, even though a different username= option had been specified to the other mounts. By using username mount option along with sec=krb5 to search for principals from keytab is supported by cifs.upcall(8) since cifs-utils-4.8. So fix this by matching username mount option in match_session() even with Kerberos. For example, the second mount below should fail with -ENOKEY as there is no 'foobar' principal in keytab (/etc/krb5.keytab). The client ends up reusing SMB session from first mount to perform the second one, which is wrong. ``` $ ktutil ktutil: add_entry -password -p testuser -k 1 -e aes256-cts Password for testuser@ZELDA.TEST: ktutil: write_kt /etc/krb5.keytab ktutil: quit $ klist -ke Keytab name: FILE:/etc/krb5.keytab KVNO Principal ---- ---------------------------------------------------------------- 1 testuser@ZELDA.TEST (aes256-cts-hmac-sha1-96) $ mount.cifs //w22-root2/scratch /mnt/1 -o sec=krb5,username=testuser $ mount.cifs //w22-root2/scratch /mnt/2 -o sec=krb5,username=foobar $ mount -t cifs | grep -Po 'username=\K\w+' testuser testuser ``` Reported-by: Oscar Santos Signed-off-by: Paulo Alcantara (Red Hat) Cc: David Howells Cc: linux-cifs@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

smb: client: fix iface port assignment in parse_server_interfaces

2026-03-25T10:03:10+00:00

commit d4c7210d2f3ea481a6481f03040a64d9077a6172 upstream. parse_server_interfaces() initializes interface socket addresses with CIFS_PORT. When the mount uses a non-default port this overwrites the configured destination port. Later, cifs_chan_update_iface() copies this sockaddr into server->dstaddr, causing reconnect attempts to use the wrong port after server interface updates. Use the existing port from server->dstaddr instead. Cc: stable@vger.kernel.org Fixes: fe856be475f7 ("CIFS: parse and store info on iface queries") Tested-by: Dr. Thomas Orgis Reviewed-by: Enzo Matsumiya Signed-off-by: Henrique Carvalho Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

smb: client: fix atomic open with O_DIRECT & O_SYNC

2026-03-25T10:03:10+00:00

commit 4a7d2729dc99437dbb880a64c47828c0d191b308 upstream. When user application requests O_DIRECT|O_SYNC along with O_CREAT on open(2), CREATE_NO_BUFFER and CREATE_WRITE_THROUGH bits were missed in CREATE request when performing an atomic open, thus leading to potentially data integrity issues. Fix this by setting those missing bits in CREATE request when O_DIRECT|O_SYNC has been specified in cifs_do_create(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Paulo Alcantara (Red Hat) Reviewed-by: David Howells Acked-by: Henrique Carvalho Cc: Tom Talpey Cc: linux-cifs@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

smb: client: Don't log plaintext credentials in cifs_set_cifscreds

2026-03-25T10:02:59+00:00

commit 2f37dc436d4e61ff7ae0b0353cf91b8c10396e4d upstream. When debug logging is enabled, cifs_set_cifscreds() logs the key payload and exposes the plaintext username and password. Remove the debug log to avoid exposing credentials. Fixes: 8a8798a5ff90 ("cifs: fetch credentials out of keyring for non-krb5 auth multiuser mounts") Cc: stable@vger.kernel.org Acked-by: Paulo Alcantara (Red Hat) Signed-off-by: Thorsten Blum Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

smb: client: fix broken multichannel with krb5+signing

2026-03-25T10:02:58+00:00

commit d9d1e319b39ea685ede59319002d567c159d23c3 upstream. When mounting a share with 'multichannel,max_channels=n,sec=krb5i', the client was duplicating signing key for all secondary channels, thus making the server fail all commands sent from secondary channels due to bad signatures. Every channel has its own signing key, so when establishing a new channel with krb5 auth, make sure to use the new session key as the derived key to generate channel's signing key in SMB2_auth_kerberos(). Repro: $ mount.cifs //srv/share /mnt -o multichannel,max_channels=4,sec=krb5i $ sleep 5 $ umount /mnt $ dmesg ... CIFS: VFS: sign fail cmd 0x5 message id 0x2 CIFS: VFS: \\srv SMB signature verification returned error = -13 CIFS: VFS: sign fail cmd 0x5 message id 0x2 CIFS: VFS: \\srv SMB signature verification returned error = -13 CIFS: VFS: sign fail cmd 0x4 message id 0x2 CIFS: VFS: \\srv SMB signature verification returned error = -13 Reported-by: Xiaoli Feng Reviewed-by: Enzo Matsumiya Signed-off-by: Paulo Alcantara (Red Hat) Cc: David Howells Cc: linux-cifs@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

smb: client: add proper locking around ses->iface_last_update

2026-03-04T12:20:12+00:00

[ Upstream commit e97dcac3dc0bd37e4b56aaa6874b572a3a461102 ] There is a missing ses->iface_lock in cifs_setup_session, around ses->iface_last_update. Signed-off-by: Henrique Carvalho Signed-off-by: Steve French Signed-off-by: Sasha Levin

smb: client: correct value for smbd_max_fragmented_recv_size

2026-03-04T12:19:44+00:00

[ Upstream commit 4a93d1ee2d0206970b6eb13fbffe07938cd95948 ] When we download a file without rdma offload or get a large directly enumeration from the server, the server might want to send up to smbd_max_fragmented_recv_size bytes, but if it is too large all our recv buffers might already be moved to the recv_io.reassembly.list and we're no longer able to grant recv credits. The maximum fragmented upper-layer payload receive size supported Assume max_payload_per_credit is smbd_max_receive_size - 24 = 1340 The maximum number would be smbd_receive_credit_max * max_payload_per_credit 1340 * 255 = 341700 (0x536C4) The minimum value from the spec is 131072 (0x20000) For now we use the logic we used in ksmbd before: (1364 * 255) / 2 = 173910 (0x2A756) Fixes: 03bee01d6215 ("CIFS: SMBD: Add SMB Direct protocol initial values and constants") Cc: Steve French Cc: Tom Talpey Cc: Long Li Cc: Namjae Jeon Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Signed-off-by: Stefan Metzmacher Signed-off-by: Steve French Signed-off-by: Sasha Levin

smb: client: fix potential UAF and double free in smb2_open_file()

2026-03-04T12:19:23+00:00

[ Upstream commit ebbbc4bfad4cb355d17c671223d0814ee3ef4eda ] Zero out @err_iov and @err_buftype before retrying SMB2_open() to prevent an UAF bug if @data != NULL, otherwise a double free. Fixes: e3a43633023e ("smb/client: fix memory leak in smb2_open_file()") Reported-by: David Howells Closes: https://lore.kernel.org/r/2892312.1770306653@warthog.procyon.org.uk Signed-off-by: Paulo Alcantara (Red Hat) Reviewed-by: David Howells Reviewed-by: ChenXiaoSong Cc: linux-cifs@vger.kernel.org Signed-off-by: Steve French Signed-off-by: Sasha Levin