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

ksmbd: fix potencial OOB in get_file_all_info() for compound requests

2026-04-11T12:16:35+00:00

[ Upstream commit beef2634f81f1c086208191f7228bce1d366493d ] When a compound request consists of QUERY_DIRECTORY + QUERY_INFO (FILE_ALL_INFORMATION) and the first command consumes nearly the entire max_trans_size, get_file_all_info() would blindly call smbConvertToUTF16() with PATH_MAX, causing out-of-bounds write beyond the response buffer. In get_file_all_info(), there was a missing validation check for the client-provided OutputBufferLength before copying the filename into FileName field of the smb2_file_all_info structure. If the filename length exceeds the available buffer space, it could lead to potential buffer overflows or memory corruption during smbConvertToUTF16 conversion. This calculating the actual free buffer size using smb2_calc_max_out_buf_len() and returning -EINVAL if the buffer is insufficient and updating smbConvertToUTF16 to use the actual filename length (clamped by PATH_MAX) to ensure a safe copy operation. Cc: stable@vger.kernel.org Fixes: e2b76ab8b5c9 ("ksmbd: add support for read compound") Reported-by: Asim Viladi Oglu Manizada Signed-off-by: Namjae Jeon Signed-off-by: Steve French [ adapted variable declarations ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ksmbd: fix memory leaks and NULL deref in smb2_lock()

2026-04-11T12:16:35+00:00

[ Upstream commit 309b44ed684496ed3f9c5715d10b899338623512 ] smb2_lock() has three error handling issues after list_del() detaches smb_lock from lock_list at no_check_cl: 1) If vfs_lock_file() returns an unexpected error in the non-UNLOCK path, goto out leaks smb_lock and its flock because the out: handler only iterates lock_list and rollback_list, neither of which contains the detached smb_lock. 2) If vfs_lock_file() returns -ENOENT in the UNLOCK path, goto out leaks smb_lock and flock for the same reason. The error code returned to the dispatcher is also stale. 3) In the rollback path, smb_flock_init() can return NULL on allocation failure. The result is dereferenced unconditionally, causing a kernel NULL pointer dereference. Add a NULL check to prevent the crash and clean up the bookkeeping; the VFS lock itself cannot be rolled back without the allocation and will be released at file or connection teardown. Fix cases 1 and 2 by hoisting the locks_free_lock()/kfree() to before the if(!rc) check in the UNLOCK branch so all exit paths share one free site, and by freeing smb_lock and flock before goto out in the non-UNLOCK branch. Propagate the correct error code in both cases. Fix case 3 by wrapping the VFS unlock in an if(rlock) guard and adding a NULL check for locks_free_lock(rlock) in the shared cleanup. Found via call-graph analysis using sqry. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Suggested-by: ChenXiaoSong Signed-off-by: Werner Kasselman Reviewed-by: ChenXiaoSong Acked-by: Namjae Jeon Signed-off-by: Steve French [ adapted rlock->c.flc_type to rlock->fl_type ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ksmbd: do not expire session on binding failure

2026-04-11T12:16:13+00:00

commit 9bbb19d21ded7d78645506f20d8c44895e3d0fb9 upstream. When a multichannel session binding request fails (e.g. wrong password), the error path unconditionally sets sess->state = SMB2_SESSION_EXPIRED. However, during binding, sess points to the target session looked up via ksmbd_session_lookup_slowpath() -- which belongs to another connection's user. This allows a remote attacker to invalidate any active session by simply sending a binding request with a wrong password (DoS). Fix this by skipping session expiration when the failed request was a binding attempt, since the session does not belong to the current connection. The reference taken by ksmbd_session_lookup_slowpath() is still correctly released via ksmbd_user_session_put(). Cc: stable@vger.kernel.org Signed-off-by: Hyunwoo Kim Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

ksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len()

2026-04-11T12:16:13+00:00

commit 0e55f63dd08f09651d39e1b709a91705a8a0ddcb upstream. After this commit (e2b76ab8b5c9 "ksmbd: add support for read compound"), response buffer management was changed to use dynamic iov array. In the new design, smb2_calc_max_out_buf_len() expects the second argument (hdr2_len) to be the offset of ->Buffer field in the response structure, not a hardcoded magic number. Fix the remaining call sites to use the correct offsetof() value. Cc: stable@vger.kernel.org Fixes: e2b76ab8b5c9 ("ksmbd: add support for read compound") Signed-off-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

ksmbd: fix use-after-free of share_conf in compound request

2026-03-25T10:03:23+00:00

[ Upstream commit c33615f995aee80657b9fdfbc4ee7f49c2bd733d ] smb2_get_ksmbd_tcon() reuses work->tcon in compound requests without validating tcon->t_state. ksmbd_tree_conn_lookup() checks t_state == TREE_CONNECTED on the initial lookup path, but the compound reuse path bypasses this check entirely. If a prior command in the compound (SMB2_TREE_DISCONNECT) sets t_state to TREE_DISCONNECTED and frees share_conf via ksmbd_share_config_put(), subsequent commands dereference the freed share_conf through work->tcon->share_conf. KASAN report: [ 4.144653] ================================================================== [ 4.145059] BUG: KASAN: slab-use-after-free in smb2_write+0xc74/0xe70 [ 4.145415] Read of size 4 at addr ffff88810430c194 by task kworker/1:1/44 [ 4.145772] [ 4.145867] CPU: 1 UID: 0 PID: 44 Comm: kworker/1:1 Not tainted 7.0.0-rc3+ #60 PREEMPTLAZY [ 4.145871] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 4.145875] Workqueue: ksmbd-io handle_ksmbd_work [ 4.145888] Call Trace: [ 4.145892] [ 4.145894] dump_stack_lvl+0x64/0x80 [ 4.145910] print_report+0xce/0x660 [ 4.145919] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 [ 4.145928] ? smb2_write+0xc74/0xe70 [ 4.145931] kasan_report+0xce/0x100 [ 4.145934] ? smb2_write+0xc74/0xe70 [ 4.145937] smb2_write+0xc74/0xe70 [ 4.145939] ? __pfx_smb2_write+0x10/0x10 [ 4.145942] ? _raw_spin_unlock+0xe/0x30 [ 4.145945] ? ksmbd_smb2_check_message+0xeb2/0x24c0 [ 4.145948] ? smb2_tree_disconnect+0x31c/0x480 [ 4.145951] handle_ksmbd_work+0x40f/0x1080 [ 4.145953] process_one_work+0x5fa/0xef0 [ 4.145962] ? assign_work+0x122/0x3e0 [ 4.145964] worker_thread+0x54b/0xf70 [ 4.145967] ? __pfx_worker_thread+0x10/0x10 [ 4.145970] kthread+0x346/0x470 [ 4.145976] ? recalc_sigpending+0x19b/0x230 [ 4.145980] ? __pfx_kthread+0x10/0x10 [ 4.145984] ret_from_fork+0x4fb/0x6c0 [ 4.145992] ? __pfx_ret_from_fork+0x10/0x10 [ 4.145995] ? __switch_to+0x36c/0xbe0 [ 4.145999] ? __pfx_kthread+0x10/0x10 [ 4.146003] ret_from_fork_asm+0x1a/0x30 [ 4.146013] [ 4.146014] [ 4.149858] Allocated by task 44: [ 4.149953] kasan_save_stack+0x33/0x60 [ 4.150061] kasan_save_track+0x14/0x30 [ 4.150169] __kasan_kmalloc+0x8f/0xa0 [ 4.150274] ksmbd_share_config_get+0x1dd/0xdd0 [ 4.150401] ksmbd_tree_conn_connect+0x7e/0x600 [ 4.150529] smb2_tree_connect+0x2e6/0x1000 [ 4.150645] handle_ksmbd_work+0x40f/0x1080 [ 4.150761] process_one_work+0x5fa/0xef0 [ 4.150873] worker_thread+0x54b/0xf70 [ 4.150978] kthread+0x346/0x470 [ 4.151071] ret_from_fork+0x4fb/0x6c0 [ 4.151176] ret_from_fork_asm+0x1a/0x30 [ 4.151286] [ 4.151332] Freed by task 44: [ 4.151418] kasan_save_stack+0x33/0x60 [ 4.151526] kasan_save_track+0x14/0x30 [ 4.151634] kasan_save_free_info+0x3b/0x60 [ 4.151751] __kasan_slab_free+0x43/0x70 [ 4.151861] kfree+0x1ca/0x430 [ 4.151952] __ksmbd_tree_conn_disconnect+0xc8/0x190 [ 4.152088] smb2_tree_disconnect+0x1cd/0x480 [ 4.152211] handle_ksmbd_work+0x40f/0x1080 [ 4.152326] process_one_work+0x5fa/0xef0 [ 4.152438] worker_thread+0x54b/0xf70 [ 4.152545] kthread+0x346/0x470 [ 4.152638] ret_from_fork+0x4fb/0x6c0 [ 4.152743] ret_from_fork_asm+0x1a/0x30 [ 4.152853] [ 4.152900] The buggy address belongs to the object at ffff88810430c180 [ 4.152900] which belongs to the cache kmalloc-96 of size 96 [ 4.153226] The buggy address is located 20 bytes inside of [ 4.153226] freed 96-byte region [ffff88810430c180, ffff88810430c1e0) [ 4.153549] [ 4.153596] The buggy address belongs to the physical page: [ 4.153750] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88810430ce80 pfn:0x10430c [ 4.154000] flags: 0x100000000000200(workingset|node=0|zone=2) [ 4.154160] page_type: f5(slab) [ 4.154251] raw: 0100000000000200 ffff888100041280 ffff888100040110 ffff888100040110 [ 4.154461] raw: ffff88810430ce80 0000000800200009 00000000f5000000 0000000000000000 [ 4.154668] page dumped because: kasan: bad access detected [ 4.154820] [ 4.154866] Memory state around the buggy address: [ 4.155002] ffff88810430c080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 4.155196] ffff88810430c100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 4.155391] >ffff88810430c180: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc [ 4.155587] ^ [ 4.155693] ffff88810430c200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 4.155891] ffff88810430c280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 4.156087] ================================================================== Add the same t_state validation to the compound reuse path, consistent with ksmbd_tree_conn_lookup(). Fixes: 5005bcb42191 ("ksmbd: validate session id and tree id in the compound request") Signed-off-by: Hyunwoo Kim Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin

ksmbd: Compare MACs in constant time

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

commit c5794709bc9105935dbedef8b9cf9c06f2b559fa upstream. To prevent timing attacks, MAC comparisons need to be constant-time. Replace the memcmp() with the correct function, crypto_memneq(). Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

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

ksmbd: Don't log keys in SMB3 signing and encryption key generation

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

[ Upstream commit 441336115df26b966575de56daf7107ed474faed ] When KSMBD_DEBUG_AUTH logging is enabled, generate_smb3signingkey() and generate_smb3encryptionkey() log the session, signing, encryption, and decryption key bytes. Remove the logs to avoid exposing credentials. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Signed-off-by: Thorsten Blum Acked-by: Namjae Jeon Signed-off-by: Steve French [ Context ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ksmbd: call ksmbd_vfs_kern_path_end_removing() on some error paths

2026-03-25T10:03:14+00:00

[ Upstream commit a09dc10d1353f0e92c21eae2a79af1c2b1ddcde8 ] There are two places where ksmbd_vfs_kern_path_end_removing() needs to be called in order to balance what the corresponding successful call to ksmbd_vfs_kern_path_start_removing() has done, i.e. drop inode locks and put the taken references. Otherwise there might be potential deadlocks and unbalanced locks which are caught like: BUG: workqueue leaked lock or atomic: kworker/5:21/0x00000000/7596 last function: handle_ksmbd_work 2 locks held by kworker/5:21/7596: #0: ffff8881051ae448 (sb_writers#3){.+.+}-{0:0}, at: ksmbd_vfs_kern_path_locked+0x142/0x660 #1: ffff888130e966c0 (&type->i_mutex_dir_key#3/1){+.+.}-{4:4}, at: ksmbd_vfs_kern_path_locked+0x17d/0x660 CPU: 5 PID: 7596 Comm: kworker/5:21 Not tainted 6.1.162-00456-gc29b353f383b #138 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 Workqueue: ksmbd-io handle_ksmbd_work Call Trace: dump_stack_lvl+0x44/0x5b process_one_work.cold+0x57/0x5c worker_thread+0x82/0x600 kthread+0x153/0x190 ret_from_fork+0x22/0x30 Found by Linux Verification Center (linuxtesting.org). Fixes: d5fc1400a34b ("smb/server: avoid deadlock when linking with ReplaceIfExists") Cc: stable@vger.kernel.org Signed-off-by: Fedor Pchelkin Acked-by: Namjae Jeon Signed-off-by: Steve French [ ksmbd_vfs_kern_path_end_removing() call -> ksmbd_vfs_kern_path_unlock() ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman