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 57B4346E01C; Tue, 21 Jul 2026 18:03:17 +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=1784656998; cv=none; b=Wn0rxWyou+vvHtOzXUWox32eZRoH6q00pOWPg2HjgpPfxCMh/JJ7lKqJpOEGMytDU7ld8g1NswmTeHrHw12x8DGBMmTxOn4ChlNA5SnOCmECJK3umywf8JsPF5fgt03pN4BXxhhs51T6cVKa15rDU/VqVhSGX3vyWeZy0j3D0ho= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784656998; c=relaxed/simple; bh=SN3meadoW6VNAly+quR01Mfry2fZD62xUyXZuP4HqMM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NS6h0+lyYhg+XAa3S4DGlfTUrSsm/Bn3ONf2ToKmFccVkvVXZMtJM41C7TFnpiSaIJGjgU0bzmGMzc0mtPBoHTRXOoI2UE1/RZgZ6LWoSH2SO/376iX026YvHkrLjaFx5DSo34qtgVmBh8Eb5knv98v1toh50oEvu7yUuePpLyU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=o4gRa5dS; 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="o4gRa5dS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BDD071F000E9; Tue, 21 Jul 2026 18:03:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784656997; bh=J2QWrc9p0ygbt3Uzm+NjhJt9iWZnbaf2AfKoU+JO2S4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=o4gRa5dSxUHafUq+jEf9iDWLaTbY4e3XX+YpTggkmEqUxsqCWYPCJ9wack1e2moEq CbzdUjaJeaT1l7CiIdYxlMHTyX04IfprWM44glWWOGePqfOU7zBwJjNgvjW7vwDljn PzOAWkzeoaD+qh5T8higS4E6pZJuuSBJ8pObCrOw= 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 6.18 0561/1611] ksmbd: fix use-after-free in same_client_has_lease() Date: Tue, 21 Jul 2026 17:11:17 +0200 Message-ID: <20260721152527.995697822@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152514.750365251@linuxfoundation.org> References: <20260721152514.750365251@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 6.18-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 6454c7a4baa450..fc2ee00cfd8100 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