From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793831921; b=fZ6nAWFXR1gUBtXpjUjOP8e5Jzj8hUL3uksuwpct6v4L+iJm+dNr7f+3siHbKoC9jVzG TsQ1t68DEM9awUn1XK3qyK0nZ7FC5diobXg9hF1ZBgU0StJTv/m0u2KIzzCgXaOAXFu4l MRWAUy4/LwD/2bTyR4V9gpq20KRuTXr9GOGvYgfFqnoFIbr/5Ncyn0L8HqWLuoVGcbXDy 63TUZJZYIA5C4ZJnVznUS3CdHVbuSITx5WXcdADZGs6aHJLUv5j/5+vBtbK32ntmMuemD klhfc+bU5XGb61z9JMuql/BkKOnR9yEy6MruVFJr2K+82IsH12LZic54+nC7pKGpuvw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831921; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=Oc2EnMbM9gcVPSf9eIJWSidhy7OF8EGuZ+DyAF8wn5Q=; b=0J+5lsPgeu5zs5KedaT8KR9utIzHw2xRsXAS4RDimVIHNYPVBSnfmmLDL91wbvOeiTci J7U2QKGbnh3GvDHWiTkh20w29srdbJdxlTpwhdTZSgyTBjIiPGn+ZW/BJI52l8lRJ5Ltx h6KOcoqk+VpDx2S0d/6qdhCBpQ9IIp+J/X66U/nNDYL2IGi2xfBxfGNbJrLayzmf3yN6t cpozT7VL+o6/twT3oO+Ro/bvX49L0eaQ1HwHapzw4xomItECl3Op6udwIEMKd00cPvEmF DZ6RL3cSK3aYCHwFzBZ6bvIuGrZ3sAVcARtBGIFsLSROsW3hMKeZWSQgRkrx0/HgNTg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=tdLsa5Gw; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B28D606A328; Wed, 4 Nov 2026 22:38:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=tdLsa5Gw Received: by smtp.kernel.org (Postfix) with ESMTPSA id 148D31F000C1; Wed, 4 Nov 2026 22:38:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831921; bh=Oc2EnMbM9gcVPSf9eIJWSidhy7OF8EGuZ+DyAF8wn5Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=tdLsa5GwGmBY0mA3EH95644MjBfe+cqVF6uIz1ErSJ/Iglo9VsZ9CHjKSCUeTrv/N C3GOnI9SdP0ePj++QriREhwyKDAeFbXXUirSwySHDHucqcvEu9XXXD9GOIVt7pfS2U JGP5T5dA1/Vw5b0Wj3ao/EJShiCjlTAPq3QlxP1o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ian Bridges , Namjae Jeon , Sasha Levin Subject: [PATCH 6.18 0995/1005] ksmbd: fix use-after-free after a failed durable reconnect Date: Wed, 4 Nov 2026 16:12:08 -0500 Message-ID: <20261104211110.904812605@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ian Bridges [ Upstream commit 248b5819591c577727930e4e255a455235fab50a ] ksmbd_reopen_durable_fd() republishes a detached durable handle in the reconnecting session's file table and takes no reference for that entry. If smb2_open() then fails, cleanup relies on the final ksmbd_fd_put() to remove the volatile id. Two reconnects of the same handle can both take a lookup reference before either attaches it. If the one that reopens first then fails and drops its references first, the other request makes the final put through ksmbd_put_durable_fd(). That frees the handle without removing the first session's table entry, so tearing that session down writes to freed memory. BUG: KASAN: slab-use-after-free in __close_file_table_ids+0x14d/0x740 [ksmbd] Call Trace: __close_file_table_ids+0x14d/0x740 [ksmbd] ksmbd_destroy_file_table+0x76/0x100 [ksmbd] ksmbd_session_destroy+0xf8/0x480 [ksmbd] ksmbd_dispose_sessions+0x13e/0x200 [ksmbd] ksmbd_conn_sessions_cleanup+0x4c3/0x6d0 [ksmbd] Freed by task 1030: __ksmbd_close_fd+0x97d/0x1000 [ksmbd] smb2_open+0x14eb/0xd9f0 [ksmbd] Commit 3515503322f4 ("ksmbd: fix durable reconnect error path file lifetime") handles a final put made by the reconnecting request, but not one made by another holder. Remove the volatile id under the file-table lock on this error path, before the references are dropped, as ksmbd_close_fd() does on the request_open path just above. Removal then no longer depends on which holder makes the final put. The stale comment in the reconnect cleanup is updated to match. A successful reconnect is unchanged. Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Cc: stable@vger.kernel.org Signed-off-by: Ian Bridges Signed-off-by: Namjae Jeon [ sashal: Adapted the cleanup call to a braced if (fp) block because the replay and request-open cleanup branches are absent. ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/smb2pdu.c | 12 +++++++----- fs/smb/server/vfs_cache.c | 28 ++++++++++++++++++++++++++++ fs/smb/server/vfs_cache.h | 2 ++ 3 files changed, 37 insertions(+), 5 deletions(-) --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -3933,8 +3933,11 @@ err_out2: if (!rsp->hdr.Status) rsp->hdr.Status = STATUS_UNEXPECTED_IO_ERROR; - if (fp) + if (fp) { + if (dh_info.reconnected && fp == dh_info.fp) + ksmbd_unpublish_reopened_fd(work, fp); ksmbd_fd_put(work, fp); + } smb2_set_err_rsp(work); ksmbd_debug(SMB, "Error response: %x\n", rsp->hdr.Status); } @@ -3942,10 +3945,9 @@ err_out2: if (dh_info.reconnected) { /* * If reconnect succeeded, fp was republished in the - * session file table. On a later error, ksmbd_fd_put() - * above drops the session reference; drop the durable - * lookup reference through the same session-aware path so - * final close removes the volatile id before freeing fp. + * session file table, and the error path above has + * already removed its volatile id. Drop the durable + * lookup reference through the same session-aware path. */ if (rc && fp == dh_info.fp) ksmbd_fd_put(work, dh_info.fp); --- a/fs/smb/server/vfs_cache.c +++ b/fs/smb/server/vfs_cache.c @@ -486,6 +486,34 @@ static void set_close_state_blocked_work spin_unlock(&fp->f_lock); } +/** + * ksmbd_unpublish_reopened_fd() - remove a reopened durable handle from the + * session file table after its CREATE failed + * @work: smb work of the failed CREATE + * @fp: durable handle republished by ksmbd_reopen_durable_fd() + * + * The reopen publishes @fp in this session's table without taking a reference + * for the entry, so the CREATE error path's puts need not be the last ones. + * Another holder of a global-table reference, such as a concurrent reconnect + * of the same handle, can drop the last one through ksmbd_put_durable_fd(), + * which frees @fp without touching this table. Remove the id here, while + * the caller still holds its references. + * + * Every path that removes the id before the final put also clears + * @fp->volatile_id under ft->lock, so a valid id is still @fp's entry. + */ +void ksmbd_unpublish_reopened_fd(struct ksmbd_work *work, struct ksmbd_file *fp) +{ + struct ksmbd_file_table *ft = &work->sess->file_table; + + write_lock(&ft->lock); + if (has_file_id(fp->volatile_id)) { + idr_remove(ft->idr, fp->volatile_id); + fp->volatile_id = KSMBD_NO_FID; + } + write_unlock(&ft->lock); +} + int ksmbd_close_fd(struct ksmbd_work *work, u64 id) { struct ksmbd_file *fp; --- a/fs/smb/server/vfs_cache.h +++ b/fs/smb/server/vfs_cache.h @@ -158,6 +158,8 @@ static inline bool ksmbd_stream_fd(struc int ksmbd_init_file_table(struct ksmbd_file_table *ft); void ksmbd_destroy_file_table(struct ksmbd_session *sess); int ksmbd_close_fd(struct ksmbd_work *work, u64 id); +void ksmbd_unpublish_reopened_fd(struct ksmbd_work *work, + struct ksmbd_file *fp); struct ksmbd_file *ksmbd_lookup_fd_fast(struct ksmbd_work *work, u64 id); struct ksmbd_file *ksmbd_lookup_foreign_fd(struct ksmbd_work *work, u64 id); struct ksmbd_file *ksmbd_lookup_fd_slow(struct ksmbd_work *work, u64 id,