kernel/linux.git/fs/smb/client, branch v6.1.178

cifs: fix lock ordering while disabling multichannel

2026-07-24T13:55:18+00:00

commit 5eef12c4e3230f2025dc46ad8c4a3bc19978e5d7 upstream. The code to handle the case of server disabling multichannel was picking iface_lock with chan_lock held. This goes against the lock ordering rules, as iface_lock is a higher order lock (even if it isn't so obvious). This change fixes the lock ordering by doing the following in that order for each secondary channel: 1. store iface and server pointers in local variable 2. remove references to iface and server in channels 3. unlock chan_lock 4. lock iface_lock 5. dec ref count for iface 6. unlock iface_lock 7. dec ref count for server 8. lock chan_lock again Since this function can only be called in smb2_reconnect, and that cannot be called by two parallel processes, we should not have races due to dropping chan_lock between steps 3 and 8. Fixes: ee1d21794e55 ("cifs: handle when server stops supporting multichannel") Reported-by: Paulo Alcantara Signed-off-by: Shyam Prasad N Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

smb: move smb_version_values to common/smbglob.h

2026-07-24T13:55:15+00:00

[ Upstream commit 34cf191bb6a349dc88ec2c4f6355fe006ac669e0 ] Merge the struct members of the server and the client: - req_capabilities: from client - header_preamble_size: from client - cap_unicode: from client - capabilities: from server, rename to req_capabilities - max_read_size: from server - max_write_size: from server - max_trans_size: from server - max_credits: from server - create_durable_size: from server - create_durable_v2_size: from server - create_mxac_size: from server - create_disk_id_size: from server - create_posix_size: from server Then move duplicate definitions to common header file. Co-developed-by: ChenXiaoSong Signed-off-by: ChenXiaoSong Signed-off-by: ZhangGuoDong Acked-by: Namjae Jeon Signed-off-by: Steve French Stable-dep-of: c1016dd1d8b2 ("ksmbd: track the connection owning a byte-range lock") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb: move some duplicate definitions to common/cifsglob.h

2026-07-24T13:55:15+00:00

[ Upstream commit d877470b59910b5c50383d634dda3782386bba51 ] In order to maintain the code more easily, move duplicate definitions to new common header file. Co-developed-by: ChenXiaoSong Signed-off-by: ChenXiaoSong Signed-off-by: ZhangGuoDong Signed-off-by: Steve French Stable-dep-of: c1016dd1d8b2 ("ksmbd: track the connection owning a byte-range lock") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb: client: resolve SWN tcon from live registrations

2026-07-24T13:55:15+00:00

[ Upstream commit ec457f9afe5ae9538bdcd58fd4cb442b9787e183 ] cifs_swn_notify() looks up a witness registration by id under cifs_swnreg_idr_mutex, drops the mutex, and then uses the registration's cached tcon pointer. That pointer is not a lifetime reference, and it is not a stable representative once cifs_get_swn_reg() lets multiple tcons for the same net/share name share one registration id. A same-share second mount can keep the cifs_swn_reg alive after the first tcon unregisters and is freed. The registration then still points at the freed first tcon, so taking tc_lock or incrementing tc_count through swnreg->tcon only moves the use-after-free earlier. Taking tc_lock while holding cifs_swnreg_idr_mutex also violates the documented CIFS lock order. Fix this by making the registration store only the stable witness identity: id, net name, share name, and notify flags. When a notify arrives, copy that identity under cifs_swnreg_idr_mutex, drop the mutex, then find and pin a live witness tcon that currently matches the net/share pair under the normal cifs_tcp_ses_lock -> tc_lock order. The notification path uses that pinned tcon directly and drops the reference when done. Registration and unregister messages now use the live tcon passed by the caller instead of a cached tcon in the registration. The final unregister send is folded into cifs_swn_unregister() while the registration is still protected by cifs_swnreg_idr_mutex. This removes the previous find/drop/reacquire raw-pointer window. The release path only removes the idr entry and frees the stable identity strings. This preserves the intended one-registration/many-tcon behavior: a registration id represents a net/share pair, and notify handling acts on a live representative selected at use time. It also preserves CLIENT_MOVE ordering for the representative tcon because the old-IP unregister is sent before cifs_swn_register() sends the new-IP register. 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 Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

cifs: Add tracing for the cifs_tcon struct refcounting

2026-07-24T13:55:15+00:00

[ Upstream commit afc23febd51c7e24361e3a9c09f3e892eb0a41ea ] Add tracing for the refcounting/lifecycle of the cifs_tcon struct, marking different events with different labels and giving each tcon its own debug ID so that the tracelines corresponding to individual tcons can be distinguished. This can be enabled with: echo 1 >/sys/kernel/debug/tracing/events/cifs/smb3_tcon_ref/enable Signed-off-by: David Howells Acked-by: Paulo Alcantara (Red Hat) cc: Shyam Prasad N cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Steve French Stable-dep-of: ec457f9afe5a ("smb: client: resolve SWN tcon from live registrations") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

cifs: Fix reacquisition of volume cookie on still-live connection

2026-07-24T13:55:14+00:00

[ Upstream commit dad80c6bff770d25f67ec25fe011730e4a463008 ] During mount, cifs_mount_get_tcon() gets a tcon resource connection record and then attaches an fscache volume cookie to it. However, it does this irrespective of whether or not the tcon returned from cifs_get_tcon() is a new record or one that's already in use. This leads to a warning about a volume cookie collision and a leaked volume cookie because tcon->fscache gets reset. Fix this be adding a mutex and a "we've already tried this" flag and only doing it once for the lifetime of the tcon. [!] Note: Looking at cifs_mount_get_tcon(), a more general solution may actually be required. Reacquiring the volume cookie isn't the only thing that function does: it also partially reinitialises the tcon record without any locking - which may cause live filesystem ops already using the tcon through a previous mount to malfunction. This can be reproduced simply by something like: mount //example.com/test /xfstest.test -o user=shares,pass=xxx,fsc mount //example.com/test /mnt -o user=shares,pass=xxx,fsc Fixes: 70431bfd825d ("cifs: Support fscache indexing rewrite") Signed-off-by: David Howells Acked-by: Paulo Alcantara (Red Hat) cc: Shyam Prasad N cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Steve French Stable-dep-of: ec457f9afe5a ("smb: client: resolve SWN tcon from live registrations") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

cifs: after disabling multichannel, mark tcon for reconnect

2026-07-24T13:55:14+00:00

[ Upstream commit 27e1fd343f80168ff456785c2443136b6b7ca3cc ] Once the server disables multichannel for an active multichannel session, on the following reconnect, the client would reduce the number of channels to 1. However, it could be the case that the tree connect was active on one of these disabled channels. This results in an unrecoverable state. This change fixes that by making sure that whenever a channel is being terminated, the session and tcon are marked for reconnect too. This could mean a few redundant tree connect calls to the server, but considering that this is not a frequent event, we should be okay. Fixes: ee1d21794e55 ("cifs: handle when server stops supporting multichannel") Signed-off-by: Shyam Prasad N Signed-off-by: Steve French Stable-dep-of: ec457f9afe5a ("smb: client: resolve SWN tcon from live registrations") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

cifs: handle when server stops supporting multichannel

2026-07-24T13:55:14+00:00

[ Upstream commit ee1d21794e55ab76505745d24101331552182002 ] When a server stops supporting multichannel, we will keep attempting reconnects to the secondary channels today. Avoid this by freeing extra channels when negotiate returns no multichannel support. Signed-off-by: Shyam Prasad N Signed-off-by: Steve French Stable-dep-of: ec457f9afe5a ("smb: client: resolve SWN tcon from live registrations") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb: client: use kvzalloc() for megabyte buffer in simple fallocate

2026-07-24T13:55:04+00:00

commit 806c00c23e3ce8eae397a40ced536ef88ae4e012 upstream. Currently in smb3_simple_fallocate_range(), a 1 MB buffer is allocated using kzalloc(). Under heavy memory fragmentation, a contiguous 1 MB block of physical memory (an order-8 allocation) may not be available, causing the allocation to fail. This failure was observed during xfstests generic/013 on a 4GB RAM test machine running fsstress: fsstress: page allocation failure: order:8, mode:0x40dc0(GFP_KERNEL|__GFP_ZERO|__GFP_COMP), nodemask=(null),cpuset=/,mems_allowed=0 Call Trace: dump_stack_lvl+0x5d/0x80 warn_alloc+0x163/0x190 __alloc_pages_slowpath.constprop.0+0x71b/0x12f0 __alloc_frozen_pages_noprof+0x2f6/0x340 alloc_pages_mpol+0xb6/0x170 ___kmalloc_large_node+0xb3/0xd0 __kmalloc_large_noprof+0x1e/0xc0 smb3_simple_falloc.isra.0+0x62b/0x960 cifs_fallocate+0xed/0x180 vfs_fallocate+0x165/0x3c0 __x64_sys_fallocate+0x48/0xa0 do_syscall_64+0xe1/0x640 entry_SYSCALL_64_after_hwframe+0x76/0x7e Node 0 Normal: 3375*4kB ... 7*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB Since this scratch buffer does not require physically contiguous memory, switch the allocation to kvzalloc(). This retains the performance benefits of kmalloc() under normal conditions, while gracefully falling back to virtually contiguous memory when physical allocation fails. Fixes: 966a3cb7c7db ("cifs: improve fallocate emulation") Cc: stable@vger.kernel.org Signed-off-by: Fredric Cover Tested-by: Fredric Cover Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

smb: client: fix overflow in passthrough ioctl bounds check

2026-07-24T13:54:57+00:00

[ Upstream commit a4f27ad055392fa164f5649e89a3637b033c5fcc ] smb2_ioctl_query_info() validates the PASSTHRU_FSCTL response payload before copying it to userspace. The payload offset and length both come from 32-bit fields. The bounds check currently adds OutputOffset and qi.input_buffer_length directly, so the addition can wrap in 32-bit arithmetic before the result is compared against the response buffer length. A malicious server can use a large OutputOffset and a small OutputCount to make the wrapped sum pass the bounds check. The later copy_to_user() then reads from io_rsp + OutputOffset, outside the response buffer. Use size_add() for the offset plus length check so overflow is treated as out of bounds. Fixes: 2b1116bbe898 ("CIFS: Use common error handling code in smb2_ioctl_query_info()") Signed-off-by: Guangshuo Li Signed-off-by: Steve French Signed-off-by: Sasha Levin