kernel/linux.git/fs/smb/client, branch v7.1-rc5

Merge tag 'v7.1-rc5-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6

2026-05-22T17:52:26+00:00

Pull smb client fixes from Steve French: - Fix missing lock - Fix dentry in use after unmounting - cifs.upcall security fix - require CAP_NET_ADMIN for swn netlink - change allocation in DUP_CTX_STR to GFP_KERNEL - minor smbdirect debug fix - handle_read_data() folio fix * tag 'v7.1-rc5-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6: smb: client: change allocation requirements in DUP_CTX_STR macro smb: client: require net admin for CIFS SWN netlink smb: smbdirect: divide, not multiply, milliseconds by 1000 cifs: Fix busy dentry used after unmounting smb: client: use data_len for SMB2 READ encrypted folioq copy smb: client: reject userspace cifs.spnego descriptions smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()

smb: client: change allocation requirements in DUP_CTX_STR macro

2026-05-21T16:16:09+00:00

Currently, the macro DUP_CTX_STR allocates new_ctx->field using GFP_ATOMIC. DUP_CTX_STR is only used in smb3_fs_context_dup(), which is never called in an atomic context. Using GFP_ATOMIC puts unnecessary pressure on emergency memory pools. Change GFP_ATOMIC to GFP_KERNEL. Signed-off-by: Fredric Cover Signed-off-by: Steve French

smb: client: require net admin for CIFS SWN netlink

2026-05-21T16:15:17+00:00

CIFS_GENL_CMD_SWN_NOTIFY is the userspace witness-notify command. The intended sender is the cifs.witness helper, but the generic-netlink operation currently has no capability flag, so any local process can send RESOURCE_CHANGE or CLIENT_MOVE notifications to the in-kernel witness handler. The same family exposes CIFS_GENL_MCGRP_SWN without multicast-group capability flags. Register messages sent to that group include the witness registration id and, for NTLM-authenticated mounts, the username, domain, and password attributes copied from the CIFS session. An unprivileged local process should not be able to join that group and receive those messages. Require CAP_NET_ADMIN for incoming SWN_NOTIFY commands with GENL_ADMIN_PERM, and require CAP_NET_ADMIN over the network namespace for joining the SWN multicast group with GENL_MCAST_CAP_NET_ADMIN. The cifs.witness service runs with the privileges needed for both operations. Fixes: fed979a7e082 ("cifs: Set witness notification handler for messages from userspace daemon") Cc: stable@vger.kernel.org Signed-off-by: Michael Bommarito Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Steve French

cifs: Fix busy dentry used after unmounting

2026-05-21T14:29:37+00:00

Since commit 340cea84f691c ("cifs: open files should not hold ref on superblock"), cifs file only holds the dentry ref_cnt, the cifs file close work(cfile->deferred) could be executed after unmounting, which will trigger a warning in generic_shutdown_super: BUG: Dentry 00000000a14a6845{i=c,n=file} still in use (1) [unmount of cifs cifs] The detailed processs is: process A process B kworker fd = open(PATH) vfs_open file->__f_path = *path // dentry->d_lockref.count = 1 cifs_open cifs_new_fileinfo cfile->dentry = dget(dentry) // dentry->d_lockref.count = 2 close(fd) __fput cifs_close queue_delayed_work(deferredclose_wq, cfile->deferred) dput(dentry) // dentry->d_lockref.count = 1 smb2_deferred_work_close _cifsFileInfo_put list_del(&cifs_file->flist) umount cleanup_mnt deactivate_super cifs_kill_sb cifs_close_all_deferred_files_sb cifs_close_all_deferred_files // cannot find cfile, skip _cifsFileInfo_put kill_anon_super generic_shutdown_super shrink_dcache_for_umount umount_check WARN ! // dentry->d_lockref.count = 1 cifsFileInfo_put_final dput(cifs_file->dentry) // dentry->d_lockref.count = 0 Fix it by flushing 'deferredclose_wq' before calling kill_anon_super. Fetch a reproducer in https://bugzilla.kernel.org/show_bug.cgi?id=221548. Fixes: 340cea84f691c ("cifs: open files should not hold ref on superblock") Cc: stable@vger.kernel.org Reviewed-by: Shyam Prasad N Signed-off-by: Zhihao Cheng Signed-off-by: Steve French

smb: client: use data_len for SMB2 READ encrypted folioq copy

2026-05-19T16:17:07+00:00

In handle_read_data() the encrypted/folioq branch (buf_len <= data_offset, reached via receive_encrypted_read for transform PDUs > CIFSMaxBufSize + MAX_HEADER_SIZE) copies the READ payload using buffer_len rather than data_len: rdata->result = cifs_copy_folioq_to_iter(buffer, buffer_len, cur_off, &rdata->subreq.io_iter); ... rdata->got_bytes = buffer_len; buffer_len comes from the SMB3 transform header OriginalMessageSize field (OriginalMessageSize - read_rsp_size); it represents the size of the decrypted message after the SMB2 header. data_len comes from the SMB2 READ response DataLength field; it represents the actual READ payload size and may be smaller than buffer_len when the decrypted message contains padding or other trailing bytes after the READ payload. The existing check `data_len > buffer_len - pad_len` only enforces an upper bound, so a server that emits OriginalMessageSize larger than read_rsp_size + pad_len + data_len passes the check and the kernel copies buffer_len bytes per response, ignoring the server-asserted DataLength. Two observable failures with a crafted server (DataLength=4, buffer_len=20000): - the kernel returns 20000 bytes per sub-request to userspace and sets got_bytes = buffer_len, even though the response claimed only 4 bytes of payload; - on a partial netfs sub-request whose iterator is sized to data_len, the over-large copy_folio_to_iter() short-reads, cifs_copy_folioq_to_iter() returns -EIO via the n != len path, and the entire netfs read collapses to -EIO even though the leading sub-requests succeeded. Use data_len for the copy length and for got_bytes so the kernel honours the server-asserted READ payload size. For well-formed servers (where buffer_len == pad_len + data_len) the change is behaviour-equivalent. Cc: stable@vger.kernel.org Signed-off-by: Jeremy Erazo Acked-by: David Howells Signed-off-by: Steve French

smb: client: reject userspace cifs.spnego descriptions

2026-05-19T15:43:05+00:00

cifs.spnego key descriptions contain authority-bearing fields such as pid, uid, creduid, and upcall_target that cifs.upcall treats as kernel-originating inputs. However, userspace can also create keys of this type through request_key(2) or add_key(2), allowing those fields to be supplied without CIFS origin. Only accept cifs.spnego descriptions while CIFS is using its private spnego_cred to request the key. Fixes: f1d662a7d5e5 ("[CIFS] Add upcall files for cifs to use spnego/kerberos") Assisted-by: avom-custom-harness:gpt-5.5-qwen3.6-mod-mix Reviewed-by: David Howells Signed-off-by: Asim Viladi Oglu Manizada Signed-off-by: Steve French

smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()

2026-05-19T15:35:12+00:00

Commit 96c4af418586 ("cifs: Fix locking usage for tcon fields") refactored cifs code to change cifs_tcp_ses_lock for tc_lock around tc_count changes. There was missing lock around tc_count increment inside smb2_find_smb_sess_tcon_unlocked(). Cc: stable@vger.kernel.org Fixes: 96c4af418586 ("cifs: Fix locking usage for tcon fields") Reviewed-by: Shyam Prasad N Signed-off-by: Henrique Carvalho Signed-off-by: Steve French

cifs: Fix undefined variables

2026-05-19T00:50:06+00:00

Fix a couple of undefined variables introduced by the patch to fix tearing on ->remote_i_size and ->zero_point. For some reason, make W=1 with gcc doesn't give undefined variable warnings (but clang does). Fixes: 2c8f4742bb76 ("netfs: Fix potential for tearing in ->remote_i_size and ->zero_point") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202605031459.eX5UbO3K-lkp@intel.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202605021450.ca5QGqLH-lkp@intel.com/ cc: Steve French cc: Paulo Alcantara cc: Matthew Wilcox cc: Christian Brauner cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Linus Torvalds

Merge tag 'vfs-7.1-rc5.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2026-05-18T14:30:31+00:00

Pull vfs fixes from Christian Brauner: "This contains a fixes for the current development cycle. Note that AI related review sometimes delays fixes a bit because we find more fixes for the fixes. I might try and send smaller but more fixes PRs if this trend keeps up. - Fix various netfslib bugs - Fix an out-of-bounds write when listing idmappings - Fix the return values in jfs_mkdir() and orangefs_mkdir() - Fix a writeback writeback array overflow in fuse - Fix a forced iversion increment on lazytime timestamp updates - Reject a negative timeval component in kern_select() - Fix error return when vfs_mkdir() fails in the cachefiles code - Fix wrong error code returned for pidns ioctls" * tag 'vfs-7.1-rc5.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (31 commits) cachefiles: Fix error return when vfs_mkdir() fails afs: Fix the locking used by afs_get_link() netfs, afs: Fix write skipping in dir/link writepages netfs: Fix netfs_read_folio() to wait on writeback netfs: Fix folio->private handling in netfs_perform_write() netfs: Fix partial invalidation of streaming-write folio netfs: Fix potential UAF in netfs_unlock_abandoned_read_pages() netfs: Fix leak of request in netfs_write_begin() error handling netfs: Fix early put of sink folio in netfs_read_gaps() netfs: Fix write streaming disablement if fd open O_RDWR netfs: Fix read-gaps to remove netfs_folio from filled folio netfs: Fix potential deadlock in write-through mode netfs: Fix streaming write being overwritten netfs: Defer the emission of trace_netfs_folio() netfs: Fix netfs_invalidate_folio() to clear dirty bit if all changes gone netfs: Fix overrun check in netfs_extract_user_iter() netfs: fix error handling in netfs_extract_user_iter() netfs: Fix potential uninitialised var in netfs_extract_user_iter() netfs: fix VM_BUG_ON_FOLIO() issue in netfs_write_begin() call netfs: Fix zeropoint update where i_size > remote_i_size ...

smb: client: avoid integer overflow in SMB2 READ length check

2026-05-14T15:55:28+00:00

SMB2 READ response validation in cifs_readv_receive() and handle_read_data() checks data_offset + data_len against the received buffer length. Both values are attacker-controlled fields from the server response and are stored as unsigned int, so the addition can wrap before the bounds check: fs/smb/client/transport.c:1259 if (!use_rdma_mr && (data_offset + data_len > buflen)) fs/smb/client/smb2ops.c:4839 else if (buf_len >= data_offset + data_len) A malicious SMB server can use this to bypass validation. In the non-encrypted receive path the client attempts an oversized socket read and stalls for the SMB response timeout (180 seconds) before reconnecting. In the SMB3 encrypted path, runtime testing shows the malformed length can reach copy_to_iter() in handle_read_data() with attacker-controlled size, where usercopy hardening stops the oversized copy before bytes reach userspace. Guard both call sites with check_add_overflow(), which is already used elsewhere in this subsystem (smb2pdu.c). On overflow, treat the response as malformed and reject with -EIO. Signed-off-by: Jeremy Erazo Signed-off-by: Steve French