From 734e99623c5b65bf2c03e35978a0b980ebc3c2f8 Mon Sep 17 00:00:00 2001 From: Henrique Carvalho Date: Mon, 3 Nov 2025 19:52:55 -0300 Subject: [PATCH 1/3] smb: client: fix potential UAF in smb2_close_cached_fid() find_or_create_cached_dir() could grab a new reference after kref_put() had seen the refcount drop to zero but before cfid_list_lock is acquired in smb2_close_cached_fid(), leading to use-after-free. Switch to kref_put_lock() so cfid_release() is called with cfid_list_lock held, closing that gap. Fixes: ebe98f1447bb ("cifs: enable caching of directories for which a lease is held") Cc: stable@vger.kernel.org Reported-by: Jay Shin Reviewed-by: Paulo Alcantara (Red Hat) Signed-off-by: Henrique Carvalho Signed-off-by: Steve French --- fs/smb/client/cached_dir.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/fs/smb/client/cached_dir.c b/fs/smb/client/cached_dir.c index b8ac7b7faf61..018055fd2cdb 100644 --- a/fs/smb/client/cached_dir.c +++ b/fs/smb/client/cached_dir.c @@ -388,11 +388,11 @@ out: * lease. Release one here, and the second below. */ cfid->has_lease = false; - kref_put(&cfid->refcount, smb2_close_cached_fid); + close_cached_dir(cfid); } spin_unlock(&cfids->cfid_list_lock); - kref_put(&cfid->refcount, smb2_close_cached_fid); + close_cached_dir(cfid); } else { *ret_cfid = cfid; atomic_inc(&tcon->num_remote_opens); @@ -438,12 +438,14 @@ int open_cached_dir_by_dentry(struct cifs_tcon *tcon, static void smb2_close_cached_fid(struct kref *ref) +__releases(&cfid->cfids->cfid_list_lock) { struct cached_fid *cfid = container_of(ref, struct cached_fid, refcount); int rc; - spin_lock(&cfid->cfids->cfid_list_lock); + lockdep_assert_held(&cfid->cfids->cfid_list_lock); + if (cfid->on_list) { list_del(&cfid->entry); cfid->on_list = false; @@ -478,7 +480,7 @@ void drop_cached_dir_by_name(const unsigned int xid, struct cifs_tcon *tcon, spin_lock(&cfid->cfids->cfid_list_lock); if (cfid->has_lease) { cfid->has_lease = false; - kref_put(&cfid->refcount, smb2_close_cached_fid); + close_cached_dir(cfid); } spin_unlock(&cfid->cfids->cfid_list_lock); close_cached_dir(cfid); @@ -487,7 +489,7 @@ void drop_cached_dir_by_name(const unsigned int xid, struct cifs_tcon *tcon, void close_cached_dir(struct cached_fid *cfid) { - kref_put(&cfid->refcount, smb2_close_cached_fid); + kref_put_lock(&cfid->refcount, smb2_close_cached_fid, &cfid->cfids->cfid_list_lock); } /* @@ -596,7 +598,7 @@ cached_dir_offload_close(struct work_struct *work) WARN_ON(cfid->on_list); - kref_put(&cfid->refcount, smb2_close_cached_fid); + close_cached_dir(cfid); cifs_put_tcon(tcon, netfs_trace_tcon_ref_put_cached_close); } @@ -762,7 +764,7 @@ static void cfids_laundromat_worker(struct work_struct *work) * Drop the ref-count from above, either the lease-ref (if there * was one) or the extra one acquired. */ - kref_put(&cfid->refcount, smb2_close_cached_fid); + close_cached_dir(cfid); } queue_delayed_work(cfid_put_wq, &cfids->laundromat_work, dir_cache_timeout * HZ); From b540de9e3b4fab3b9e10f30714a6f5c1b2a50ec3 Mon Sep 17 00:00:00 2001 From: Shuhao Fu Date: Tue, 4 Nov 2025 23:13:15 +0800 Subject: [PATCH 2/3] smb: client: fix refcount leak in smb2_set_path_attr Fix refcount leak in `smb2_set_path_attr` when path conversion fails. Function `cifs_get_writable_path` returns `cfile` with its reference counter `cfile->count` increased on success. Function `smb2_compound_op` would decrease the reference counter for `cfile`, as stated in its comment. By calling `smb2_rename_path`, the reference counter of `cfile` would leak if `cifs_convert_path_to_utf16` fails in `smb2_set_path_attr`. Fixes: 8de9e86c67ba ("cifs: create a helper to find a writeable handle by path name") Acked-by: Henrique Carvalho Signed-off-by: Shuhao Fu Signed-off-by: Steve French --- fs/smb/client/smb2inode.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c index 09e3fc81d7cb..69cb81fa0d3a 100644 --- a/fs/smb/client/smb2inode.c +++ b/fs/smb/client/smb2inode.c @@ -1294,6 +1294,8 @@ static int smb2_set_path_attr(const unsigned int xid, struct cifs_tcon *tcon, smb2_to_name = cifs_convert_path_to_utf16(to_name, cifs_sb); if (smb2_to_name == NULL) { rc = -ENOMEM; + if (cfile) + cifsFileInfo_put(cfile); goto smb2_rename_path; } in_iov.iov_base = smb2_to_name; From 4012abe8a78fbb8869634130024266eaef7081fe Mon Sep 17 00:00:00 2001 From: Joshua Rogers Date: Fri, 7 Nov 2025 00:09:37 +0800 Subject: [PATCH 3/3] smb: client: validate change notify buffer before copy SMB2_change_notify called smb2_validate_iov() but ignored the return code, then kmemdup()ed using server provided OutputBufferOffset/Length. Check the return of smb2_validate_iov() and bail out on error. Discovered with help from the ZeroPath security tooling. Signed-off-by: Joshua Rogers Reviewed-by: Paulo Alcantara (Red Hat) Cc: stable@vger.kernel.org Fixes: e3e9463414f61 ("smb3: improve SMB3 change notification support") Signed-off-by: Steve French --- fs/smb/client/smb2pdu.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index b0739a2661bf..8b4a4573e9c3 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -4054,9 +4054,12 @@ replay_again: smb_rsp = (struct smb2_change_notify_rsp *)rsp_iov.iov_base; - smb2_validate_iov(le16_to_cpu(smb_rsp->OutputBufferOffset), - le32_to_cpu(smb_rsp->OutputBufferLength), &rsp_iov, + rc = smb2_validate_iov(le16_to_cpu(smb_rsp->OutputBufferOffset), + le32_to_cpu(smb_rsp->OutputBufferLength), + &rsp_iov, sizeof(struct file_notify_information)); + if (rc) + goto cnotify_exit; *out_data = kmemdup((char *)smb_rsp + le16_to_cpu(smb_rsp->OutputBufferOffset), le32_to_cpu(smb_rsp->OutputBufferLength), GFP_KERNEL);