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 69897417D7E; Thu, 30 Jul 2026 15:25:03 +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=1785425104; cv=none; b=awfeMv22MvjQIa0KPf5qNNsfDogvmKKiSuR9+u2tOghGmpEGy22KhielQJdsZAxQbhZxovXSFQXybEB2SpqxeOChVrKs2Vsns/V83lfrRzDXpsg8aaWKTSSyAf2K5XEmpyN2z0vUQCXhqc2vqP1kYRNe4/lEAhZBjPTgxRRr2sk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785425104; c=relaxed/simple; bh=EK1wz2woO93O+zjqMABXguMzsq3H6x3/FSnz/IGns8M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=H9neSZAtniixogizwO9D/tbgfh5YrEjjLAB2baitqPxPIXVGayBGtWSJNSOBigDSbSZc/yk3TqRQDz7cN7RB1CPMaaJZS5LXlRPpGljXgJ0M/JEpL1zvp0Njj1WkxvnNZiR07vhzp7rLBVOQDJg1rbLtw3llY+yTDKN20jjFeo0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RACmDe/A; 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="RACmDe/A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BB6471F000E9; Thu, 30 Jul 2026 15:25:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785425103; bh=D+9g4/Ij9LzD9MDTovq0Lq7OuNraF6+oSJXVD38lBD0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=RACmDe/AEZFRTGGxlwfg41uMpgvWwCe1c/nge6DBtfhNpfIGk9jpUrIMmC4QRerck 2qYXzfjXbtZSrgXQoWTLwf82BX0wTpKpoBXUOObpCIEiVQQeKGqnkYB4u8ReG8Oxev IoQqEBe0um66+Qi5pauvi5msT124fTgV3F/BYNZA= 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 6.18 599/675] ksmbd: validate num_subauth when copying ACE in set_ntacl_dacl Date: Thu, 30 Jul 2026 16:15:29 +0200 Message-ID: <20260730141457.848973733@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141445.110192266@linuxfoundation.org> References: <20260730141445.110192266@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: 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 b09bc8d9389a2a..173469d112f101 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