kernel/linux.git/fs/smb/server/connection.c, branch v7.1

ksmbd: fix kernel-doc warnings from ksmbd_conn_get/put()

2026-05-02T02:49:35+00:00

The kernel test robot reported W=1 build warnings for ksmbd_conn_get() and ksmbd_conn_put() due to missing parameter descriptions. Add the @conn description to fix these warnings. Reported-by: kernel test robot Signed-off-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: centralize ksmbd_conn final release to plug transport leak

2026-05-02T02:49:35+00:00

ksmbd_conn_free() is one of four sites that can observe the last refcount drop of a struct ksmbd_conn. The other three fs/smb/server/connection.c ksmbd_conn_r_count_dec() fs/smb/server/oplock.c __free_opinfo() fs/smb/server/vfs_cache.c session_fd_check() end the conn with a bare kfree(), skipping ida_destroy(&conn->async_ida) and conn->transport->ops->free_transport(conn->transport). Whenever one of them is the last putter, the embedded async_ida and the entire transport struct leak -- for TCP, that is also the struct socket and the kvec iov. __free_opinfo() being a final putter is not theoretical. opinfo_put() queues the callback via call_rcu(&opinfo->rcu, free_opinfo_rcu), so ksmbd_server_terminate_conn() can deposit N opinfo releases in RCU and have ksmbd_conn_free() run in the handler thread before any of them fire. ksmbd_conn_free() then observes refcnt > 0 and short-circuits; the last RCU-delivered __free_opinfo() falls onto its bare kfree(conn) branch and the transport is lost. A/B validation in a QEMU/virtme guest, mounting //127.0.0.1/testshare: each iteration holds 8 files open via sleep processes, force-closes TCP with "ss -K sport = :445", kills the holders, lazy-umounts; repeated 10 times, then ksmbd shutdown and kmemleak scan. state conn_alloc conn_free tcp_free opi_rcu kmemleak ---------- ---------- --------- -------- ------- -------- pre-patch 20 20 10 160 7 with patch 20 20 20 160 0 Pre-patch conn_free=20 with tcp_free=10 directly demonstrates the bare-kfree paths skipping transport cleanup; kmemleak backtraces point into struct tcp_transport / iov. With this patch tcp_free matches conn_free at 20/20 and kmemleak is clean. Move the per-struct final release into __ksmbd_conn_release_work() and route the three bare-kfree final-put sites through a new ksmbd_conn_put(). Those sites now pair ida_destroy() and free_transport() with kfree(conn) regardless of which holder happens to release the last reference. stop_sessions() only triggers the transport shutdown and does not itself drop the last conn reference, so it is unaffected. The centralized release reaches sock_release() -> tcp_close() -> lock_sock_nested() (might_sleep) from every final putter, including __free_opinfo() invoked from an RCU softirq callback, which trips CONFIG_DEBUG_ATOMIC_SLEEP. Defer the release to a dedicated ksmbd_conn_wq workqueue so ksmbd_conn_put() is safe from any non-sleeping context. Make ksmbd_file own a strong connection reference while fp->conn is non-NULL so durable-preserve and final-close paths cannot dereference a stale connection. ksmbd_open_fd() and ksmbd_reopen_durable_fd() take the reference via ksmbd_conn_get() (the latter also reorders the fp->conn / fp->tcon assignments before __open_id() so the published fp is never observed with fp->conn == NULL); session_fd_check() and __ksmbd_close_fd() drop it via ksmbd_conn_put(). With that invariant, session_fd_check() can take a local conn pointer once and use it across the m_op_list and lock_list iterations even though op->conn puts may otherwise drop the last reference. At module exit the workqueue is flushed and destroyed after rcu_barrier(), so any release queued by a trailing RCU callback is drained before the inode hash and module text go away. Fixes: ee426bfb9d09 ("ksmbd: add refcnt to ksmbd_conn struct") Signed-off-by: DaeMyung Kang Acked-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: rewrite stop_sessions() with restartable iteration

2026-04-29T15:25:37+00:00

stop_sessions() walks conn_list with hash_for_each() and, for every entry, drops conn_list_lock across the transport ->shutdown() call before re-acquiring the read lock to continue the loop. The hash walk relies on cross-iteration state (the current bucket and the hlist position), which is not preserved across unlock/relock: if another thread performs a list mutation during the unlocked window, the ongoing iteration becomes unreliable and can re-visit connections that have already been handled or skip connections that have not. The outer `if (!hash_empty(conn_list)) goto again;` retry masks the symptom in the common case but does not address the unsafe iteration itself. Reframe the loop so it never relies on iterator state across unlock/relock. Under conn_list_lock held for read, pick the first connection whose ->shutdown() has not yet been issued by this path, pin it by taking an extra reference, record that fact on the connection and mark it EXITING while still inside the locked walk, then drop the lock. Then call ->shutdown() outside the lock, drop the pin (freeing the connection if the handler already released its reference), and restart from the top. Use a new per-connection flag, conn->stop_called, as the "shutdown issued from stop_sessions()" marker rather than reusing the status state. ksmbd_conn_set_exiting() is also invoked by ksmbd_sessions_deregister() on sibling channels of a multichannel session without issuing a transport shutdown, so treating KSMBD_SESS_EXITING as "already handled here" would skip connections that still need shutdown() to wake their handler out of recv(), leaving the outer retry waiting indefinitely for the hash to drain. stop_sessions() is serialised by init_lock in ksmbd_conn_transport_destroy(), so writing stop_called under the read lock has no other writer. Set EXITING inside the locked walk so the selection, the stop_called marker, and the status transition all happen together, and guard against regressing a connection that has already advanced to KSMBD_SESS_RELEASING on its own (for example, if the handler exited its receive loop for an unrelated reason between teardown steps). When the pin drop is the last put, release the transport and pair ida_destroy(&target->async_ida) with the ida_init() done in ksmbd_conn_alloc(), so stop_sessions() retiring a connection on its own does not leak the xarray backing of the embedded async_ida. The outer retry with msleep() is kept to wait for handler threads to reach ksmbd_conn_free() and drain the hash. Observed with an instrumented build that logs one line per visit and widens the unlocked window before ->shutdown() by 200 ms, under five concurrent cifs mounts (nosharesock, one connection each): * Current code: the same connection address is revisited many times during a single stop_sessions() call and ->shutdown() is invoked well beyond the number of live connections before the hash finally drains. * Rewritten code: each live connection produces exactly one ->shutdown() call; the function returns as soon as the hash is empty. Functional teardown via `ksmbd.control --shutdown` with the same five mounts completes cleanly on the rewritten path. Performance is observably unchanged. Tearing down N concurrent nosharesock cifs connections with `ksmbd.control --shutdown` + `rmmod ksmbd` takes essentially the same wall time before and after the rewrite: N before after 10 4.93s 5.34s 30 7.34s 7.03s 50 7.31s 7.01s (3-run avg: 7.04s vs 7.25s) 100 6.98s 6.78s 200 6.77s 6.89s and the number of ->shutdown() calls equals the number of live connections on both paths when the race is not widened. The teardown is dominated by the msleep(100)-based outer retry waiting for handler threads to run ksmbd_conn_free(), not by the iteration itself; the restartable loop's worst-case O(N^2) visit cost is in the microseconds even at N=200 and sits far below the msleep(100) granularity. Applied alone on top of ksmbd-for-next-next, this patch does not introduce a new leak site. Under the same reproducer (10x concurrent-holders + ss -K + ksmbd.control --shutdown + rmmod), the tree still shows the pre-existing per-connection transport leak count that arises when the last refcount drop lands in one of ksmbd_conn_r_count_dec(), __free_opinfo() or session_fd_check() - all of which end with a bare kfree() today. kmemleak backtraces for the unreferenced objects point into the TCP accept path (sk_clone -> inet_csk_clone_lock, sock_alloc_inode) and none involve stop_sessions(). Plugging those bare-kfree sites is the responsibility of the follow-up patch. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Signed-off-by: DaeMyung Kang Acked-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: destroy async_ida in ksmbd_conn_free()

2026-04-22T13:11:23+00:00

When per-connection async_ida was converted from a dynamically allocated ksmbd_ida to an embedded struct ida, ksmbd_ida_free() was removed from the connection teardown path but no matching ida_destroy() was added. The connection is therefore freed with the IDA's backing xarray still intact. The kernel IDA API expects ida_init() and ida_destroy() to be paired over an object's lifetime, so add the missing cleanup before the connection is freed. No leak has been observed in testing; this is a pairing fix to match the IDA lifetime rules, not a response to a reproduced regression. Fixes: d40012a83f87 ("cifsd: declare ida statically") Signed-off-by: DaeMyung Kang Acked-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: reset rcount per connection in ksmbd_conn_wait_idle_sess_id()

2026-04-22T13:11:23+00:00

rcount is intended to be connection-specific: 2 for curr_conn, 1 for every other connection sharing the same session. However, it is initialised only once before the hash iteration and is never reset. After the loop visits curr_conn, later sibling connections are also checked against rcount == 2, so a sibling with req_running == 1 is incorrectly treated as idle. This makes the outcome depend on the hash iteration order: whether a given sibling is checked against the loose (< 2) or the strict (< 1) threshold is decided by whether it happens to be visited before or after curr_conn. The function's contract is "wait until every connection sharing this session is idle" so that destroy_previous_session() can safely tear the session down. The latched rcount violates that contract and reopens the teardown race window the wait logic was meant to close: destroy_previous_session() may proceed before sibling channels have actually quiesced, overlapping session teardown with in-flight work on those connections. Recompute rcount inside the loop so each connection is compared against its own threshold regardless of iteration order. This is a code-inspection fix for an iteration-order-dependent logic error; a targeted reproducer would require SMB3 multichannel with in-flight work on a sibling channel landing after curr_conn in hash order, which is not something that can be triggered reliably. Fixes: 76e98a158b20 ("ksmbd: fix race condition between destroy_previous_session() and smb2 operations()") Cc: stable@vger.kernel.org Signed-off-by: DaeMyung Kang Acked-by: Namjae Jeon Signed-off-by: Steve French

smb: server: no longer use smbdirect_socket_set_custom_workqueue()

2026-04-16T02:58:24+00:00

smbdirect.ko has global workqueues now, so we should use these default once. Cc: Namjae Jeon Cc: Steve French Cc: Tom Talpey Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Signed-off-by: Stefan Metzmacher Acked-by: Namjae Jeon Signed-off-by: Steve French

smb: server: remove unused ksmbd_transport_ops.prepare()

2026-04-16T02:58:24+00:00

This is no longer needed for smbdirect. Cc: Namjae Jeon Cc: Steve French Cc: Tom Talpey Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Signed-off-by: Stefan Metzmacher Acked-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: fix mechToken leak when SPNEGO decode fails after token alloc

2026-04-12T23:07:55+00:00

The kernel ASN.1 BER decoder calls action callbacks incrementally as it walks the input. When ksmbd_decode_negTokenInit() reaches the mechToken [2] OCTET STRING element, ksmbd_neg_token_alloc() allocates conn->mechToken immediately via kmemdup_nul(). If a later element in the same blob is malformed, then the decoder will return nonzero after the allocation is already live. This could happen if mechListMIC [3] overrunse the enclosing SEQUENCE. decode_negotiation_token() then sets conn->use_spnego = false because both the negTokenInit and negTokenTarg grammars failed. The cleanup at the bottom of smb2_sess_setup() is gated on use_spnego: if (conn->use_spnego && conn->mechToken) { kfree(conn->mechToken); conn->mechToken = NULL; } so the kfree is skipped, causing the mechToken to never be freed. This codepath is reachable pre-authentication, so untrusted clients can cause slow memory leaks on a server without even being properly authenticated. Fix this up by not checking check for use_spnego, as it's not required, so the memory will always be properly freed. At the same time, always free the memory in ksmbd_conn_free() incase some other failure path forgot to free it. Cc: Namjae Jeon Cc: Steve French Cc: Sergey Senozhatsky Cc: Tom Talpey Cc: linux-cifs@vger.kernel.org Cc: Assisted-by: gregkh_clanker_t1000 Signed-off-by: Greg Kroah-Hartman Acked-by: Namjae Jeon Signed-off-by: Steve French

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

ksmbd: fix non-IPv6 build

2026-02-10T18:58:10+00:00

The newly added procfs code fails to build when CONFIG_IPv6 is disabled: fs/smb/server/connection.c: In function 'proc_show_clients': fs/smb/server/connection.c:47:58: error: 'struct ksmbd_conn' has no member named 'inet6_addr'; did you mean 'inet_addr'? 47 | seq_printf(m, "%-20pI6c", &conn->inet6_addr); | ^~~~~~~~~~ | inet_addr make[7]: *** [scripts/Makefile.build:279: fs/smb/server/connection.o] Error 1 fs/smb/server/mgmt/user_session.c: In function 'show_proc_sessions': fs/smb/server/mgmt/user_session.c:215:65: error: 'struct ksmbd_conn' has no member named 'inet6_addr'; did you mean 'inet_addr'? 215 | seq_printf(m, " %-40pI6c", &chan->conn->inet6_addr); | ^~~~~~~~~~ | inet_addr Rearrange the condition to allow adding a simple preprocessor conditional. Fixes: b38f99c1217a ("ksmbd: add procfs interface for runtime monitoring and statistics") Signed-off-by: Arnd Bergmann Acked-by: Namjae Jeon Signed-off-by: Steve French