kernel/linux.git/fs/cifs, branch v5.15.213

smb: client: harden POSIX SID length parsing

2026-07-24T13:51:59+00:00

[ Upstream commit 7ad2bcf2441430bb2e918fb3ef9a90d775a6e422 ] posix_info_sid_size() reads sid[1] to obtain the subauthority count, but its existing boundary check still accepts buffers with only one remaining byte. Require two bytes before reading sid[1] so all client paths that reuse the helper reject truncated POSIX SIDs safely. Fixes: 349e13ad30b4 ("cifs: add smb2 POSIX info level") Cc: stable@vger.kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Assisted-by: Codex:gpt-5.4 Signed-off-by: Zihan Xi Signed-off-by: Ren Wei Signed-off-by: Steve French Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb: client: use unaligned reads in parse_posix_ctxt()

2026-07-24T13:51:59+00:00

[ Upstream commit b86467cd2691192ad4809a5a6e922fc24b8e9839 ] The server controls create-context DataOffset, so the POSIX context data pointer may be misaligned on strict-alignment architectures. Use get_unaligned_le32() when reading nlink, reparse_tag, and mode. Fixes: 69dda3059e7a ("cifs: add SMB2_open() arg to return POSIX data") Cc: stable@vger.kernel.org Signed-off-by: Zihan Xi Signed-off-by: Ren Wei Signed-off-by: Steve French Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb: client: mask server-provided mode to 07777 in modefromsid

2026-07-24T13:51:59+00:00

[ Upstream commit e3d9c7160d483fc8f9e225aafad8ecbbc43f3151 ] When modefromsid is active, parse_dacl() applies the server-provided sub_auth[2] value from the NFS mode SID to cf_mode without masking to 07777. Apply the correct masking, same as in the read path. Fixes: e2f8fbfb8d09c ("cifs: get mode bits from special sid on stat") Signed-off-by: Norbert Manthey Assisted-by: Kiro:claude-opus-4.6 Cc: stable@vger.kernel.org Signed-off-by: Steve French Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb: client: resolve SWN tcon from live registrations

2026-07-24T13:51:59+00:00

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 (cherry picked from commit ec457f9afe5ae9538bdcd58fd4cb442b9787e183) [ sashal: 5.15 adaptations: cifs_swn_resource_state_changed() keeps the per-channel GlobalMid_Lock tcpStatus reconnect loop (5.15 lacks cifs_signal_cifsd_for_reconnect(), v5.17), switched from swnreg->tcon to the tcon argument; cifs_swn_get_tcon() drops the tc_lock pair and checks tcon->tidStatus == CifsExiting instead of tcon->status == TID_EXITING -- 5.15 has no tc_lock, tc_count and tidStatus are protected by the already-held cifs_tcp_ses_lock; tcon->tree_name is tcon->treeName in 5.15; trace.h hunks applied to fs/cifs/trace.h (pre fs/smb/client move) ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

cifs: Add tracing for the cifs_tcon struct refcounting

2026-07-24T13:51:59+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

smb: client: Fix next buffer leak in receive_encrypted_standard()

2026-07-24T13:51:59+00:00

[ Upstream commit 1c6267a1d5cf4c73b656f8181b310cbbb3e4767b ] receive_encrypted_standard() allocates next_buffer before checking whether the number of compound PDUs already reached MAX_COMPOUND. If the limit check fails, the function returns immediately and the newly allocated next_buffer is not assigned to server->smallbuf/server->bigbuf, making it leaked. Move the MAX_COMPOUND check before allocating next_buffer. Fixes: b24df3e30cbf ("cifs: update receive_encrypted_standard to handle compounded responses") Cc: stable@vger.kernel.org Signed-off-by: Haoxiang Li Signed-off-by: Steve French Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb: client: restrict implied bcc[0] exemption to responses without data area

2026-07-24T13:51:57+00:00

[ Upstream commit 53b7c271f06be4dd5cfc8c6ef552a8355c891a7f ] smb2_check_message() has a long-standing quirk that accepts a response whose calculated length is one byte larger than the bytes actually received ("server can return one byte more due to implied bcc[0]"). This was introduced to accommodate servers that omit the trailing bcc[0] overlap byte when no data area is present. However, the exemption is applied unconditionally, regardless of whether the command actually carries a data area (has_smb2_data_area[]). When a response with a data area is subject to the +1 exemption, the reported data can extend one byte beyond the bytes actually received, yet smb2_check_message() still accepts it. The subsequent decoder then reads past the end of the receive buffer. This is reachable during NEGOTIATE and SESSION_SETUP, before the session is established. The resulting out-of-bounds reads are visible under KASAN when mounting against a non-conforming server; both the SPNEGO/negTokenInit and the NTLMSSP challenge decoders are affected: BUG: KASAN: slab-out-of-bounds in asn1_ber_decoder+0x16a7/0x1b00 Read of size 1 at addr ffff8880084d67c0 by task mount.cifs/81 CPU: 1 UID: 0 PID: 81 Comm: mount.cifs Not tainted 7.1.0-rc6 #1 Call Trace: dump_stack_lvl+0x4e/0x70 print_report+0x157/0x4c9 kasan_report+0xce/0x100 asn1_ber_decoder+0x16a7/0x1b00 decode_negTokenInit+0x19/0x30 SMB2_negotiate+0x31d9/0x4c90 cifs_negotiate_protocol+0x1f2/0x3f0 cifs_get_smb_ses+0x93f/0x17e0 cifs_mount_get_session+0x7f/0x3a0 cifs_mount+0xb4/0xcf0 cifs_smb3_do_mount+0x23a/0x1500 smb3_get_tree+0x3b0/0x630 vfs_get_tree+0x82/0x2d0 fc_mount+0x10/0x1b0 path_mount+0x50d/0x1de0 __x64_sys_mount+0x20b/0x270 do_syscall_64+0xee/0x590 entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task 85: kmem_cache_alloc_noprof+0x106/0x380 mempool_alloc_noprof+0x116/0x1e0 cifs_small_buf_get+0x31/0x80 allocate_buffers+0x10d/0x2b0 cifs_demultiplex_thread+0x1d5/0x1d50 kthread+0x2c6/0x390 ret_from_fork+0x36e/0x5a0 ret_from_fork_asm+0x1a/0x30 The buggy address is located 0 bytes to the right of allocated 448-byte region [ffff8880084d6600, ffff8880084d67c0) which belongs to the cache cifs_small_rq of size 448 BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+0x36/0x50 Read of size 329 at addr ffff88800726c678 by task mount.cifs/89 CPU: 0 UID: 0 PID: 89 Comm: mount.cifs Tainted: G B 7.1.0-rc6 #1 Call Trace: dump_stack_lvl+0x4e/0x70 print_report+0x157/0x4c9 kasan_report+0xce/0x100 kasan_check_range+0x10f/0x1e0 __asan_memcpy+0x23/0x60 kmemdup_noprof+0x36/0x50 decode_ntlmssp_challenge+0x457/0x680 SMB2_sess_auth_rawntlmssp_negotiate+0x6f0/0xcb0 SMB2_sess_setup+0x219/0x4f0 cifs_setup_session+0x248/0xaf0 cifs_get_smb_ses+0xf79/0x17e0 cifs_mount_get_session+0x7f/0x3a0 cifs_mount+0xb4/0xcf0 cifs_smb3_do_mount+0x23a/0x1500 smb3_get_tree+0x3b0/0x630 vfs_get_tree+0x82/0x2d0 fc_mount+0x10/0x1b0 path_mount+0x50d/0x1de0 __x64_sys_mount+0x20b/0x270 do_syscall_64+0xee/0x590 entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task 93: kmem_cache_alloc_noprof+0x106/0x380 mempool_alloc_noprof+0x116/0x1e0 cifs_small_buf_get+0x31/0x80 allocate_buffers+0x10d/0x2b0 cifs_demultiplex_thread+0x1d5/0x1d50 kthread+0x2c6/0x390 ret_from_fork+0x36e/0x5a0 ret_from_fork_asm+0x1a/0x30 The buggy address is located 120 bytes inside of allocated 448-byte region [ffff88800726c600, ffff88800726c7c0) which belongs to the cache cifs_small_rq of size 448 Restrict the +1 exemption to responses that have no data area, so that it still covers the bcc[0] omission it was meant for. When a data area is present, the +1 discrepancy instead means the reported data length overruns the received buffer, so the response must be rejected. Fixes: 093b2bdad322 ("CIFS: Make demultiplex_thread work with SMB2 code") Cc: stable@vger.kernel.org Signed-off-by: Shoichiro Miyamoto Signed-off-by: Steve French Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

cifs: remove unused server parameter from calc_smb_size()

2026-07-24T13:51:57+00:00

[ Upstream commit 68ed14496b032b0c9ef21b38ee45c6c8f3a18ff1 ] This parameter is unused by the called function Reviewed-by: Paulo Alcantara (SUSE) Signed-off-by: Enzo Matsumiya Signed-off-by: Steve French Stable-dep-of: 53b7c271f06b ("smb: client: restrict implied bcc[0] exemption to responses without data area") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

smb2: small refactor in smb2_check_message()

2026-07-24T13:51:57+00:00

[ Upstream commit da3847894fddc27ca95d5ac0012f444a77a5e0c3 ] If the command is SMB2_IOCTL, OutputLength and OutputContext are optional and can be zero, so return early and skip calculated length check. Move the mismatched length message to the end of the check, to avoid unnecessary logs when the check was not a real miscalculation. Also change the pr_warn_once() to a pr_warn() so we're sure to get a log for the real mismatches. Signed-off-by: Enzo Matsumiya Signed-off-by: Steve French Stable-dep-of: 53b7c271f06b ("smb: client: restrict implied bcc[0] exemption to responses without data area") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

cifs: remove check of list iterator against head past the loop body

2026-07-24T13:51:57+00:00

[ Upstream commit 00c796eecba4898194ea549679797ee28f89a92f ] When list_for_each_entry() completes the iteration over the whole list without breaking the loop, the iterator value will be a bogus pointer computed based on the head element. While it is safe to use the pointer to determine if it was computed based on the head element, either with list_entry_is_head() or &pos->member == head, using the iterator variable after the loop should be avoided. In preparation to limit the scope of a list iterator to the list traversal loop, use a dedicated pointer to point to the found element [1]. Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1] Reviewed-by: Paulo Alcantara (SUSE) Signed-off-by: Jakob Koschel Signed-off-by: Steve French Stable-dep-of: 53b7c271f06b ("smb: client: restrict implied bcc[0] exemption to responses without data area") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman