From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B07613770B; Tue, 21 Jul 2026 20:38:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784666317; cv=none; b=HMCH7xXneh2beTeM84dTRBlWo+ZPPT9hYVv9H2fIn37Yt8teyDENzFiFKG3YjoQctbtxKzldat2bzoI5xDDLVF/ARTlftG4lhKjWapIC8pWbGQGNCiYaocIawEwWzlsbu8p2VeUVEgAapyXEmZMOqT9Kv5to1HXPHuUpujg+C0M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784666317; c=relaxed/simple; bh=felRFW/vQ5gl1Tq8lqm2XTcYQCX8bhtZzZn0vjq6NNY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=g/R0k6QqAfMZKacOnrfjd9jnWlEyilm5/gcyNtunN0UCNhdZbcYxE8e/h21/0hzH0p77B/JrDSSghXwxdd8ToDBS2DgGV9aDrgWq8bZ3ULtw1qa5vuxgqVXF9T88fQTVpPztH1GOV2OCXQyzHBopd0xyUoS/BXvXWDr9soOlvq4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=E9o8CZFW; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="E9o8CZFW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 210771F000E9; Tue, 21 Jul 2026 20:38:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784666316; bh=LEHZRpVs+RnBETElb+Cf9XVwomLMZpcKx7x8hPZyuUE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=E9o8CZFWrQmIBgXpLisqFtbfg1MbL3KyZuMQLOmtEcSj+nm5JJ1HDoeNqSOkoEFvJ okU4np76aXIqipRNXQ9PMot+yY3Meh1QeBxMFJoMvS0P/ySAnvWpQd+WveNRhQxcKs LqYHVcKHULuhFJXW5JvcVEMsNEbU7RZolOYqBji8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Guangshuo Li , Namjae Jeon , Steve French , Sasha Levin Subject: [PATCH 6.6 0600/1266] ksmbd: fix use-after-free in same_client_has_lease() Date: Tue, 21 Jul 2026 17:17:17 +0200 Message-ID: <20260721152455.290031998@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152441.786066624@linuxfoundation.org> References: <20260721152441.786066624@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Guangshuo Li [ Upstream commit 65b655f65c3ca1ab5d598d3832bb0ff531725858 ] same_client_has_lease() returns an opinfo pointer from ci->m_op_list after dropping ci->m_lock without taking a reference. smb_grant_oplock() then dereferences that pointer in copy_lease() and when checking breaking_cnt. A concurrent close can remove the old lease from ci->m_op_list and drop the last reference before the caller uses the returned pointer, leading to a use-after-free. Take a reference when same_client_has_lease() selects an existing lease, drop any previous match while scanning, and release the returned reference in smb_grant_oplock() after copying the lease state. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Signed-off-by: Guangshuo Li Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/smb/server/oplock.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/smb/server/oplock.c b/fs/smb/server/oplock.c index bba17ea84023e2..1d2e06e34a9a35 100644 --- a/fs/smb/server/oplock.c +++ b/fs/smb/server/oplock.c @@ -531,7 +531,12 @@ static struct oplock_info *same_client_has_lease(struct ksmbd_inode *ci, ret = compare_guid_key(opinfo, client_guid, lctx->lease_key); if (ret) { + if (!atomic_inc_not_zero(&opinfo->refcount)) + continue; + if (m_opinfo) + opinfo_put(m_opinfo); m_opinfo = opinfo; + /* skip upgrading lease about breaking lease */ if (atomic_read(&opinfo->breaking_cnt)) continue; @@ -1249,6 +1254,7 @@ int smb_grant_oplock(struct ksmbd_work *work, int req_op_level, u64 pid, if (atomic_read(&m_opinfo->breaking_cnt)) opinfo->o_lease->flags = SMB2_LEASE_FLAG_BREAK_IN_PROGRESS_LE; + opinfo_put(m_opinfo); goto out; } } -- 2.53.0