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=1792677224; b=WGHX1p6JWSR+PBya/+0kjaj3kzY0beHDJEmdViwo20fnHuczGijxGeXT+Uy7u9mHT0dD MP9akdQAJUE6NyBD7+YueboLcbv7RHasl1xFFWJ6PAYg80WRmlISw2YPKNyqEDkycApMU 0HdGh20RNMz/Nktug8qR6J+TShRwotv4UgcNmIrKrRX/FLe6Vyba2UIth6VoSiBRIkDYv XfvtI8P/1P6Pcox6vMWC/fqayAVa4EMzl7aP0F1nFKpqyGN8YCDUtpWb13qbZR389mNjX 7DDd84vu8+KepThvgFHfa6180X1AcV7x4jwIVKZiPSnIlfc7JnUUkEBP1vXjjDlAhoA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792677224; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=MdpaPJ1N2kP/L0eh96ryje4XCJXnWrvZ5bzdfClkWLU=; b=ZmYm+9pxaP1Y0ZzvgyGNhce5nIXfzbOiQqznrXN46y68EfHqCBUx4Qcxfebqx5bFFK3X vnvzxXIch0qkeqi0dIMx1/9kigojLNVbzzB64wqQz+fM1zvQEnJ2y+1rM+ORRPJ2Ydkgk PZqdQ9TEyjO/5MQLXrgXU0LK3wdhDYqJFgMrTGVcF2/ZSyAvAR+NG+C34LGMSWeYhThAb h0JzmcnsZdYZX3+EYgVXlvwaC0dWb6dBDmT7ZXoks50AhHLQIWnVyNXL0XeAppdhUy0lW Bw87J/88aRQ6gMaebfDZMf/X4lZoUsc0wV7JdWQALQ487oidMye2VCpKAOR+HHexGyg== 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=eRvRdz5P; 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 5C88160A260D for ; Thu, 22 Oct 2026 13:53:44 +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=eRvRdz5P Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7CF071F000C2; Thu, 22 Oct 2026 13:53:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792677224; bh=MdpaPJ1N2kP/L0eh96ryje4XCJXnWrvZ5bzdfClkWLU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=eRvRdz5PfDT4aj1hvDF1iNFLz4WLsWOYGJSFbOfsPO44FQLHOX0wHDuhdpgFtzV/0 DUYCPoMirRZfmGB2gh3n3EekNTNxGYGZ/4pTowj3WwDMjcq/Wtv+YxhsODRkl1C4uT vIob8h7nlDfYRmc8p8IAiilY9gsvVxW9HFOGMGi1/X/XuCmQdEbT//+sx0pNE68XTZ vYKXbzjRLlk09ejRPJtMSL1617QROr/WLM7ZVaf4RwJLCaX2pD66CA+7fXe4m2b4XY QfcyNEDKwvyrBUEfar1fdNZ9K3w8+cbTlNf/38k9I1QStnkKV375zx8Fe33wTscxno Q5uwOY42oZMjg== From: Chuck Lever To: NeilBrown , Jeff Layton , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: Subject: [PATCH v1 02/17] xdrgen: Reject out-of-range short values on decode Date: Thu, 22 Oct 2026 09:53:26 -0400 Message-ID: <20261022135341.14265-3-cel@kernel.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261022135341.14265-1-cel@kernel.org> References: <20261022135341.14265-1-cel@kernel.org> X-Mailing-List: linux-nfs@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 RFC 4506 does not define a 16-bit integer type. xdrgen's "short" follows rpcgen, whose runtime decodes the type in libtirpc's xdr_short() by reading one XDR_UNIT as a long and assigning it to a short with a plain cast. xdrgen_decode_short() mirrors that cast, so an XDR_UNIT carrying a value outside the sign-extended 16-bit range decodes as the low sixteen bits of that word. A decoder's semantic checks on the narrowed value cannot see the discarded high bits, the same defect xdrgen_decode_unsigned_short() had for the unsigned type. Nothing in XDR or rpcgen requires a decoder to accept such a word. Fail the decode when the wire word, read as a signed 32-bit value, lies outside S16_MIN to S16_MAX. xdrgen_encode_short() and libtirpc's xdr_short() sign-extend an s16 to fill the XDR_UNIT, so a conforming peer never sends such a word. No NFS specification uses a signed short, so no generated decoder calls xdrgen_decode_short() today. The check keeps the signed and unsigned builtins consistent. Signed-off-by: Chuck Lever --- include/linux/sunrpc/xdrgen/_builtins.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/include/linux/sunrpc/xdrgen/_builtins.h b/include/linux/sunrpc/xdrgen/_builtins.h index 6b389181dc7b..55c514bae5d1 100644 --- a/include/linux/sunrpc/xdrgen/_builtins.h +++ b/include/linux/sunrpc/xdrgen/_builtins.h @@ -48,18 +48,20 @@ xdrgen_encode_bool(struct xdr_stream *xdr, bool val) /* * De facto (non-standard but commonly implemented) signed short type: - * - Wire sends sign-extended 32-bit value (e.g., 0xFFFFFFFF) - * - be32_to_cpup() returns u32 (0xFFFFFFFF) - * - Explicit (s16) cast truncates to 16 bits (0xFFFF = -1) + * 16-bit integer sign-extended to fill one XDR_UNIT. */ static inline bool xdrgen_decode_short(struct xdr_stream *xdr, s16 *ptr) { __be32 *p = xdr_inline_decode(xdr, XDR_UNIT); + s32 val; if (unlikely(!p)) return false; - *ptr = (s16)be32_to_cpup(p); + val = be32_to_cpup(p); + if (unlikely(val < S16_MIN || val > S16_MAX)) + return false; + *ptr = val; return true; } -- 2.56.0