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=1793725070; b=HvGjUOMze7aH2a6JzzM8/5DL1AyOvfApX6GuhqIZZSLXGR2r/MFMyrCoftvq53ZlNZsc isAq4RlzDfX7Mp5ZcpEZI/3CExH4Acui/bsP3PV5N8gbaq7KY0WjFwaD1vy/VLu8joncR YJq3cY/jdvqvZci0QcPTxcST+MxtQN0iZj9OLapQqr8dWBJ4OHwq5PYUZnMzHM3IQYUe3 EcZ+bZBD5ejvKjacJ8IrHIq8jMWj817a0RXy7/2vT4WGpdg5i1rLCbUp6RhFhIJI/5COp RU5d8Ne8kndGjlWE63hXCIguvujcPu4dGyfJVxKVpQo0pShqTAgNa6X4pOLDvKyrFZw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793725070; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=ItrjoZDzo4cAyvkXxLCg9/VMNDCt/+Rq+2z6cSjiMz8=; b=1lbhrB5nijCxzTdsNhsaqeUuhCMcOblN7dta0gf1K3PiIofMiYjcC0yziSgdYftguRth LxyzC6Z+MWMO6jqsVfXblXcHISUC9DULJ3zILBpnVr0E5dGtPxOZ/DjY5tN9zLknK1pw4 7JbbNiUDshYpZmhByrJr5B4ruST+QjZHobtPwNGXM1dMwctX2aeT1ZocrPrlq/jV+nfb3 BamLb305xQ/ZrORc1tguTczc6uAVKAJwVKed/icu5hUjHod7zwEFWt8ejv8WNdPufiSfD PAiziwcq12ABer5FJBS6MaMXbzWewpgqNQBjLc26n2Rdqwsi4Ex8FEGziu3kPKLebig== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=V3B7IPFc; 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 464DC606A324 for ; Tue, 3 Nov 2026 16:57:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=V3B7IPFc Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E0E31F00919; Tue, 3 Nov 2026 16:57:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793725069; bh=ItrjoZDzo4cAyvkXxLCg9/VMNDCt/+Rq+2z6cSjiMz8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=V3B7IPFccptuStWGhM6yU3L+ZSXeel+0Jn7yzCLZ3Sm9AsCw6PmcjRCz2PosRmwU2 vXFZTJpnemlbZL5QTMLlEp5iT8t/IdCieaIOj1cPQLsr1vH96v6+r0ifAFR6ZqNXLa SvkmCecToBVwXIDtqxAnTKNbwIDlMazaZY9NHzpUIcy4UcjURsyvTKR3gjxpJBkC2m Op2XTbUkbmSh3jFli2b+dJ9P0pZaA7wse42YP6ixBqOZXmA/qQuraXGr5gb8OMxRK/ hznqN3Y/oaGxzXIHmOFFosheMv64wKbsbjl86KI+I+EFUJEKmYtKIUCKgTr++girWq Dkb8QiDj+g20w== From: Sasha Levin To: stable@vger.kernel.org Cc: Ian Bridges , Namjae Jeon , Sasha Levin Subject: [PATCH 7.3.y 2/2] ksmbd: fix out-of-bounds read when padding the final compound response Date: Tue, 3 Nov 2026 11:57:47 -0500 Message-ID: <20261103165719.643173-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261103165719.643173-1-sashal@kernel.org> References: <2026110339-undesired-vagabond-3610@gregkh> <20261103165719.643173-1-sashal@kernel.org> 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 From: Ian Bridges [ Upstream commit 714f27729121d59f103ca4dad7b0c2d1c125cd71 ] Compound response handling pads the last response of a compound to an 8-byte boundary by growing the final iov and the RFC1002 length. smb2_allocate_rsp_buf() allocates exactly response_sz. A command can fill the response buffer to within 7 bytes of its end, for example a QUERY_INFO whose output is bounded only by the space left. The padding can then run past the allocation, and ksmbd_tcp_writev() reads those bytes when it sends the response. BUG: KASAN: slab-out-of-bounds in _copy_from_iter+0x744/0x10e0 Call Trace: _copy_from_iter+0x744/0x10e0 tcp_sendmsg_locked+0x2290/0x3f80 ksmbd_tcp_writev+0x10c7/0x1ab0 [ksmbd] Allocate room for the padding when the request is a compound, as smb2_read() and smb2_read_pipe() do for their payloads. response_sz is unchanged, so commands still fill only up to it, and kvzalloc() zeroes the padding. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Signed-off-by: Ian Bridges Signed-off-by: Namjae Jeon Signed-off-by: Sasha Levin --- fs/smb/server/smb2pdu.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index e5bbd003e3599..fa1c8f613ddd8 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -876,7 +876,7 @@ int smb2_allocate_rsp_buf(struct ksmbd_work *work) struct smb_version_values *vals = work->conn->vals; size_t small_sz = MAX_CIFS_SMALL_BUFFER_SIZE; size_t large_sz = small_sz + vals->max_trans_size; - size_t sz = small_sz; + size_t sz = small_sz, pad_sz = 0; int cmd = le16_to_cpu(hdr->Command); if (cmd == SMB2_IOCTL_HE || cmd == SMB2_QUERY_DIRECTORY_HE) @@ -902,10 +902,17 @@ int smb2_allocate_rsp_buf(struct ksmbd_work *work) } /* allocate large response buf for chained commands */ - if (le32_to_cpu(hdr->NextCommand) > 0) + if (le32_to_cpu(hdr->NextCommand) > 0) { sz = large_sz; + /* + * is_chained_smb2_message() pads the last response of a + * compound to 8 bytes, which can take it past response_sz. + * Leave room for the padding. kvzalloc() zeroes it. + */ + pad_sz = ALIGN(sz - sizeof(__be32), 8) - (sz - sizeof(__be32)); + } - work->response_buf = kvzalloc(sz, KSMBD_DEFAULT_GFP); + work->response_buf = kvzalloc(sz + pad_sz, KSMBD_DEFAULT_GFP); if (!work->response_buf) return -ENOMEM; -- 2.53.0