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=1794061828; b=oYmZhpGmq4SNJJMc+0tqZbqYAqeyPRwBDXm3WqXRQxksFxMQaNaF2jUvrkzFuFbw/R6Z sVv2ftdy+MxFSIPkEvjB75VCyObvKmPOiFunfX2F4hgczF1FpFHfRJsDuNTv7C0lPSNJs pe7Pgomus12fMFAHDyAi4ITSd0XBwrjNrYCoqKwQrzX8ZTEN0Bmi7amOrzMX1PGgSTk/I Fd2wXl8+HyXlq1vLVaYXIvtpBaMvBtM2YtJhCXbcmTgPi+O+JaJMP7/Bcoq6vAxuSMSYW o9Gu6w7lFF/YNWBoRM49ySse82uSRiWZh+inGsOeFIkPwvR0/jnfSn/qT9J1ydGfgNg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794061828; 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=D6u9DiwJGF+NbrG3NFqqQFS3Zs1+6CY3LWkGEeYpt3U=; b=sL73XTfwruFBM1EQdtBcB5gc3rh+m6fWL2PALKMJgeS5jdZUlb+UyZdsC7/gQy9fdf02 tjKXVor1Avvjm0eFMh7oNAH2KLmc1mvU794cvMPYuixgeTs82EWOS1/gE4W7iRsmimSTf T2cNFJg6abvLVuT4vBk7W4rvCUGl/5iMdQz0uRho4guExgZwOPo9TwcThBw2tbuKmrCjR gnLvMyavg9EVA5JvzwMTe9RtMOZiOzrpoUjx1YFNy/XUa4isnJub5/45p7tC2BYPTnF0S m++wlRCxUVHkNOdDs5U1lDKbYOZmeAhN7Ndatt6tHVJYErOSh4N8qCl5fkzvr6y8bSw== 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=OxfCGDfz; 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 2416E606A326; Sat, 7 Nov 2026 14:30:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=OxfCGDfz Received: by smtp.kernel.org (Postfix) with ESMTPSA id C6B551F0089F; Sat, 7 Nov 2026 14:30:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794061828; bh=D6u9DiwJGF+NbrG3NFqqQFS3Zs1+6CY3LWkGEeYpt3U=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=OxfCGDfzlznWt1LQQQvFDD0LxrqI3QcZxY84OOrT7aJZarQXg/jCiJDeIbB0og5tA 2RP/sopWeWXuUfpQDdN9oK6CS14JaotUcztV0Wo1QVDvr7UTVpOziTUkT0gx/NyqSo 4iPZl4QOMBENUhGJPIDkYgM2h6dl9TjKBWhRuviY= 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 6.12 0850/1536] ksmbd: fix use-after-free after a failed durable reconnect Date: Sat, 7 Nov 2026 08:47:46 -0500 Message-ID: <20261107135021.420936479@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134957.653319350@linuxfoundation.org> References: <20261107134957.653319350@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-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 cleanup to the simpler if (fp) error path in smb2_open() ] Signed-off-by: Sasha Levin --- 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(-) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index 4b42196ade240..b5a71ca407b65 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -3900,8 +3900,11 @@ int smb2_open(struct ksmbd_work *work) 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); } @@ -3909,10 +3912,9 @@ int smb2_open(struct ksmbd_work *work) 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); diff --git a/fs/smb/server/vfs_cache.c b/fs/smb/server/vfs_cache.c index 5aa46e41ac6f8..bde487fb30054 100644 --- a/fs/smb/server/vfs_cache.c +++ b/fs/smb/server/vfs_cache.c @@ -486,6 +486,34 @@ static void set_close_state_blocked_works(struct ksmbd_file *fp) 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; diff --git a/fs/smb/server/vfs_cache.h b/fs/smb/server/vfs_cache.h index 342fcde36ea9e..c8f457bb41b34 100644 --- a/fs/smb/server/vfs_cache.h +++ b/fs/smb/server/vfs_cache.h @@ -155,6 +155,8 @@ static inline bool ksmbd_stream_fd(struct ksmbd_file *fp) 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, -- 2.53.0