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 8A9312D7393; Thu, 30 Jul 2026 14:54:13 +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=1785423254; cv=none; b=ta6YB9NuKNt1mQIRz+nSsyh48hT5emJOCYDAX0a2tQCZYkORyYLpYkSgfKCUivwEUuNk0GS1nLgfitWDEqCqahaK6b9yt+wtdZ7Cm5SM7v0qP3BniB4f42q/xqd+Ob3oyhHkJrghBg87blRA6mSohYBeaGySANWAZaGNBYSP6v8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423254; c=relaxed/simple; bh=C8I2nH5Fx1WI/WpzPdS2FHdkOevlB87FxDWJ4XDJbOM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=o8KroCdjzTFpf++zXAcX8r/ZjryDB1OTgF/Qs80TKANDx2DObfYp06A0k+7oyi22pbqhEqtslDT7WbM5sjtuFZDMjovLGLVEwzw22WdPzFBestNGu26royUb2BzuPsizFGiC9zbkA82LgTZLPhGrlQl8RgFUDT20mlLLciZwYb0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Bs32yezG; 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="Bs32yezG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5ABB1F000E9; Thu, 30 Jul 2026 14:54:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785423253; bh=Id4JNr/rLz8uqL+w34UInB5KzMBqZ8CNNP697c4KCqs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Bs32yezGVS7KA4vm0r5ENx45INWuHM1L7RbDqbzfbuuU4dS1wRVV9Z+Z9RqRMc1us MBHgOrYwZ0BVNh7M05KoYtGsdWuaIK8xpSoL+ePRxMjYHXHfq4MIthyUak+VuR5Pt1 1PcM0YeibitVm3528588WZZCx5ddGg+uxxA2DJwI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Haofeng Li , ChenXiaoSong , Namjae Jeon , Steve French , Wentao Guan , Sasha Levin Subject: [PATCH 7.1 720/744] ksmbd: validate num_subauth when copying ACE in set_ntacl_dacl Date: Thu, 30 Jul 2026 16:16:33 +0200 Message-ID: <20260730141459.584594830@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141444.267951807@linuxfoundation.org> References: <20260730141444.267951807@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 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Haofeng Li commit 47f0b34f6bc98ed85bfdc293e8f3e432ec24958d upstream. set_ntacl_dacl() copies each ACE from the attacker-controlled stored security descriptor verbatim into the response DACL without checking sid.num_subauth. The ACE bytes (including an unchecked num_subauth) originate from an authenticated SMB2_SET_INFO(SecInfo=DACL) that is stored raw via ksmbd_vfs_set_sd_xattr(); parse_dacl() rejects a bad ACE with `break` rather than an error, so parse_sec_desc() still returns success and the malformed SD reaches the xattr intact. On a subsequent SMB2_QUERY_INFO(SecInfo=DACL) for an inode carrying a POSIX access ACL, build_sec_desc() -> set_ntacl_dacl() -> set_posix_acl_entries_dacl() walks the copied ACEs and reads ntace->sid.sub_auth[ntace->sid.num_subauth - 1] with num_subauth taken straight from the stored SD. Since sub_auth[] is fixed at SID_MAX_SUB_AUTHORITIES (15), a crafted num_subauth (e.g. 255) drives an out-of-bounds heap read of ~1 KB with an offset fully controlled by an authenticated client. The sibling functions already gate this field: parse_dacl() -- num_subauth == 0 || > SID_MAX_SUB_AUTHORITIES parse_sid() -- num_subauth > SID_MAX_SUB_AUTHORITIES smb_copy_sid() -- min_t(u8, num_subauth, SID_MAX_SUB_AUTHORITIES) set_ntacl_dacl() is the lone inconsistent path that omits the check. Add the same num_subauth validation in set_ntacl_dacl() before copying the ACE, matching the gate already enforced by parse_dacl(). Signed-off-by: Haofeng Li Reviewed-by: ChenXiaoSong Suggested-by: Namjae Jeon Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Wentao Guan Signed-off-by: Sasha Levin --- fs/smb/server/smbacl.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/smb/server/smbacl.c b/fs/smb/server/smbacl.c index fc9937cedb012b..9c59c8f73b6675 100644 --- a/fs/smb/server/smbacl.c +++ b/fs/smb/server/smbacl.c @@ -745,12 +745,18 @@ static void set_ntacl_dacl(struct mnt_idmap *idmap, if (nt_ace_size > aces_size) break; + if (ntace->sid.num_subauth == 0 || + ntace->sid.num_subauth > SID_MAX_SUB_AUTHORITIES) + goto next_ace; + memcpy((char *)pndace + size, ntace, nt_ace_size); if (check_add_overflow(size, nt_ace_size, &size)) break; + num_aces++; + +next_ace: aces_size -= nt_ace_size; ntace = (struct smb_ace *)((char *)ntace + nt_ace_size); - num_aces++; } } -- 2.53.0