From 705c79101ccf9edea5a00d761491a03ced314210 Mon Sep 17 00:00:00 2001 From: Wang Zhaolong Date: Mon, 7 Jul 2025 09:09:26 +0800 Subject: [PATCH 1/4] smb: client: fix use-after-free in cifs_oplock_break A race condition can occur in cifs_oplock_break() leading to a use-after-free of the cinode structure when unmounting: cifs_oplock_break() _cifsFileInfo_put(cfile) cifsFileInfo_put_final() cifs_sb_deactive() [last ref, start releasing sb] kill_sb() kill_anon_super() generic_shutdown_super() evict_inodes() dispose_list() evict() destroy_inode() call_rcu(&inode->i_rcu, i_callback) spin_lock(&cinode->open_file_lock) <- OK [later] i_callback() cifs_free_inode() kmem_cache_free(cinode) spin_unlock(&cinode->open_file_lock) <- UAF cifs_done_oplock_break(cinode) <- UAF The issue occurs when umount has already released its reference to the superblock. When _cifsFileInfo_put() calls cifs_sb_deactive(), this releases the last reference, triggering the immediate cleanup of all inodes under RCU. However, cifs_oplock_break() continues to access the cinode after this point, resulting in use-after-free. Fix this by holding an extra reference to the superblock during the entire oplock break operation. This ensures that the superblock and its inodes remain valid until the oplock break completes. Link: https://bugzilla.kernel.org/show_bug.cgi?id=220309 Fixes: b98749cac4a6 ("CIFS: keep FileInfo handle live during oplock break") Reviewed-by: Paulo Alcantara (Red Hat) Signed-off-by: Wang Zhaolong Signed-off-by: Steve French --- fs/smb/client/file.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c index e9212da32f01..1421bde045c2 100644 --- a/fs/smb/client/file.c +++ b/fs/smb/client/file.c @@ -3088,7 +3088,8 @@ void cifs_oplock_break(struct work_struct *work) struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo, oplock_break); struct inode *inode = d_inode(cfile->dentry); - struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb); + struct super_block *sb = inode->i_sb; + struct cifs_sb_info *cifs_sb = CIFS_SB(sb); struct cifsInodeInfo *cinode = CIFS_I(inode); struct cifs_tcon *tcon; struct TCP_Server_Info *server; @@ -3098,6 +3099,12 @@ void cifs_oplock_break(struct work_struct *work) __u64 persistent_fid, volatile_fid; __u16 net_fid; + /* + * Hold a reference to the superblock to prevent it and its inodes from + * being freed while we are accessing cinode. Otherwise, _cifsFileInfo_put() + * may release the last reference to the sb and trigger inode eviction. + */ + cifs_sb_active(sb); wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS, TASK_UNINTERRUPTIBLE); @@ -3170,6 +3177,7 @@ void cifs_oplock_break(struct work_struct *work) cifs_put_tlink(tlink); out: cifs_done_oplock_break(cinode); + cifs_sb_deactive(sb); } static int cifs_swap_activate(struct swap_info_struct *sis, From b220bed63330c0e1733dc06ea8e75d5b9962b6b6 Mon Sep 17 00:00:00 2001 From: Wang Zhaolong Date: Sat, 5 Jul 2025 10:51:18 +0800 Subject: [PATCH 2/4] smb: client: fix use-after-free in crypt_message when using async crypto The CVE-2024-50047 fix removed asynchronous crypto handling from crypt_message(), assuming all crypto operations are synchronous. However, when hardware crypto accelerators are used, this can cause use-after-free crashes: crypt_message() // Allocate the creq buffer containing the req creq = smb2_get_aead_req(..., &req); // Async encryption returns -EINPROGRESS immediately rc = enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req); // Free creq while async operation is still in progress kvfree_sensitive(creq, ...); Hardware crypto modules often implement async AEAD operations for performance. When crypto_aead_encrypt/decrypt() returns -EINPROGRESS, the operation completes asynchronously. Without crypto_wait_req(), the function immediately frees the request buffer, leading to crashes when the driver later accesses the freed memory. This results in a use-after-free condition when the hardware crypto driver later accesses the freed request structure, leading to kernel crashes with NULL pointer dereferences. The issue occurs because crypto_alloc_aead() with mask=0 doesn't guarantee synchronous operation. Even without CRYPTO_ALG_ASYNC in the mask, async implementations can be selected. Fix by restoring the async crypto handling: - DECLARE_CRYPTO_WAIT(wait) for completion tracking - aead_request_set_callback() for async completion notification - crypto_wait_req() to wait for operation completion This ensures the request buffer isn't freed until the crypto operation completes, whether synchronous or asynchronous, while preserving the CVE-2024-50047 fix. Fixes: b0abcd65ec54 ("smb: client: fix UAF in async decryption") Link: https://lore.kernel.org/all/8b784a13-87b0-4131-9ff9-7a8993538749@huaweicloud.com/ Cc: stable@vger.kernel.org Reviewed-by: Paulo Alcantara (Red Hat) Signed-off-by: Wang Zhaolong Signed-off-by: Steve French --- fs/smb/client/smb2ops.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c index 1468c16ea9b8..cb659256d219 100644 --- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -4316,6 +4316,7 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst, u8 key[SMB3_ENC_DEC_KEY_SIZE]; struct aead_request *req; u8 *iv; + DECLARE_CRYPTO_WAIT(wait); unsigned int crypt_len = le32_to_cpu(tr_hdr->OriginalMessageSize); void *creq; size_t sensitive_size; @@ -4366,7 +4367,11 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst, aead_request_set_crypt(req, sg, sg, crypt_len, iv); aead_request_set_ad(req, assoc_data_len); - rc = enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req); + aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, + crypto_req_done, &wait); + + rc = crypto_wait_req(enc ? crypto_aead_encrypt(req) + : crypto_aead_decrypt(req), &wait); if (!rc && enc) memcpy(&tr_hdr->Signature, sign, SMB2_SIGNATURE_SIZE); From 83898e4a858387c88cd7456f713cb8fd49440cf9 Mon Sep 17 00:00:00 2001 From: Bharath SM Date: Tue, 1 Jul 2025 00:23:03 +0530 Subject: [PATCH 3/4] smb: invalidate and close cached directory when creating child entries MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When a parent lease key is passed to the server during a create operation while holding a directory lease, the server may not send a lease break to the client. In such cases, it becomes the client’s responsibility to ensure cache consistency. This led to a problem where directory listings (e.g., `ls` or `readdir`) could return stale results after a new file is created. eg: ls /mnt/share/ touch /mnt/share/file1 ls /mnt/share/ In this scenario, the final `ls` may not show `file1` due to the stale directory cache. For now, fix this by marking the cached directory as invalid if using the parent lease key during create, and explicitly closing the cached directory after successful file creation. Fixes: 037e1bae588eacf ("smb: client: use ParentLeaseKey in cifs_do_create") Signed-off-by: Bharath SM Signed-off-by: Steve French --- fs/smb/client/dir.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/smb/client/dir.c b/fs/smb/client/dir.c index 1c6e5389c51f..5223edf6d11a 100644 --- a/fs/smb/client/dir.c +++ b/fs/smb/client/dir.c @@ -190,6 +190,7 @@ static int cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned int disposition; struct TCP_Server_Info *server = tcon->ses->server; struct cifs_open_parms oparms; + struct cached_fid *parent_cfid = NULL; int rdwr_for_fscache = 0; __le32 lease_flags = 0; @@ -313,10 +314,10 @@ static int cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned if (!tcon->unix_ext && (mode & S_IWUGO) == 0) create_options |= CREATE_OPTION_READONLY; + retry_open: if (tcon->cfids && direntry->d_parent && server->dialect >= SMB30_PROT_ID) { - struct cached_fid *parent_cfid; - + parent_cfid = NULL; spin_lock(&tcon->cfids->cfid_list_lock); list_for_each_entry(parent_cfid, &tcon->cfids->entries, entry) { if (parent_cfid->dentry == direntry->d_parent) { @@ -327,6 +328,7 @@ static int cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned memcpy(fid->parent_lease_key, parent_cfid->fid.lease_key, SMB2_LEASE_KEY_SIZE); + parent_cfid->dirents.is_valid = false; } break; } From 8767cb3fbd514c4cf85b4f516ca30388e846f540 Mon Sep 17 00:00:00 2001 From: Steve French Date: Mon, 14 Jul 2025 22:16:19 -0500 Subject: [PATCH 4/4] Fix SMB311 posix special file creation to servers which do not advertise reparse support Some servers (including Samba), support the SMB3.1.1 POSIX Extensions (which use reparse points for handling special files) but do not properly advertise file system attribute FILE_SUPPORTS_REPARSE_POINTS. Although we don't check for this attribute flag when querying special file information, we do check it when creating special files which causes them to fail unnecessarily. If we have negotiated SMB3.1.1 POSIX Extensions with the server we can expect the server to support creating special files via reparse points, and even if the server fails the operation due to really forbidding creating special files, then it should be no problem and is more likely to return a more accurate rc in any case (e.g. EACCES instead of EOPNOTSUPP). Allow creating special files as long as the server supports either reparse points or the SMB3.1.1 POSIX Extensions (note that if the "sfu" mount option is specified it uses a different way of storing special files that does not rely on reparse points). Cc: Fixes: 6c06be908ca19 ("cifs: Check if server supports reparse points before using them") Acked-by: Ralph Boehme Acked-by: Paulo Alcantara (Red Hat) Signed-off-by: Steve French --- fs/smb/client/smb2inode.c | 3 ++- fs/smb/client/smb2ops.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c index 2a3e46b8e15a..a11a2a693c51 100644 --- a/fs/smb/client/smb2inode.c +++ b/fs/smb/client/smb2inode.c @@ -1346,7 +1346,8 @@ struct inode *smb2_get_reparse_inode(struct cifs_open_info_data *data, * empty object on the server. */ if (!(le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS)) - return ERR_PTR(-EOPNOTSUPP); + if (!tcon->posix_extensions) + return ERR_PTR(-EOPNOTSUPP); oparms = CIFS_OPARMS(cifs_sb, tcon, full_path, SYNCHRONIZE | DELETE | diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c index cb659256d219..938a8a7c5d21 100644 --- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -5260,7 +5260,8 @@ static int smb2_make_node(unsigned int xid, struct inode *inode, if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) { rc = cifs_sfu_make_node(xid, inode, dentry, tcon, full_path, mode, dev); - } else if (le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS) { + } else if ((le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS) + || (tcon->posix_extensions)) { rc = smb2_mknod_reparse(xid, inode, dentry, tcon, full_path, mode, dev); }