From nobody Mon Apr 6 19:37:01 2026 Received: from mail-pl1-f170.google.com (mail-pl1-f170.google.com [209.85.214.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 61ED9364945 for ; Wed, 18 Mar 2026 06:48:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.170 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773816538; cv=none; b=SzMzC7OhapV4/ZAT/uQej7FQffMF6dH4/fzZ3d7DsIFEzNV/GUJfjoURHB/ITRd4r1CxY4bW4FC4tsURHUH2JzzAlkB4dg/dtfL+kFOe2WrRIJx+IGhFweLKLKCSm2FbkeSEWQZ0sEbfatxRFrADxioSXgEYPVV5MpgKRCc03YI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773816538; c=relaxed/simple; bh=Qj1QkGketFTLM6FhMiga1uXkk9E+QIhjnrMOjTAq2ZY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=fV7o3v/Jvyq6o2Hed4rMPpq/+i3MJ8H3/1jmdjPnWSphzVB/TQ1LeB/s4BBtd9vrxMnrT18eBfM5whMD5YgfpyWzAXf31mDKTDq7kkj8hD/CzEWkSn1Pv4ihtD8YIaTIcbJkDe0mLsdx4H5ZLnszGna2pglPQEQR8fGsgS0koUk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=YbT3p7Iw; arc=none smtp.client-ip=209.85.214.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YbT3p7Iw" Received: by mail-pl1-f170.google.com with SMTP id d9443c01a7336-2ab46931cf1so5342045ad.0 for ; Tue, 17 Mar 2026 23:48:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1773816537; x=1774421337; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=cwVGV5+seuNEQDXpmjKxLE/WMiIEl6PzK6G5vJJXXZA=; b=YbT3p7IwofRR4B71gvIvW4EYvPkkHFAZKnxd325boEmEBFUL/kF+aumEjLzU6wTeVi J4wJ1MlBDsN9y0A5iwvtdSJ6WmSy1fgLfWvB1FcCA0c8hEajcFDp+KLme9ciDi1sDa9W wnj86JwfQquO42V7nWuafBoYJRLPlLE19MJG+CpRN+HqUHcmgB/T5sXbp7udQ4DobENp Xa/wkzsznNFEVBZm/0k3L+K7vwji1nj4hG6WTj/rGJcx2MP6k5mzBQJ72ADF+v+qddPj LNIAfnrimodMiZ9rkFX+rnCICM9/mmWOs4sgDi4BOs8m1Dd4IA6kPtUJd0AnV3ZN6DcP 1olQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773816537; x=1774421337; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=cwVGV5+seuNEQDXpmjKxLE/WMiIEl6PzK6G5vJJXXZA=; b=hT7WiruUGbZNvot7YwLm0dydnLT90MwdNupd0odxdhgT+8hkRcv9sosSC4QZ/znP/Q o/18mR5YBzfSri7njQqzwayk7iOnnYnHbCW7nc9ZHTAEnsa7fKA2DeQMV/6gg0X70R1R o8yD9mpU7KHu6GB1+vMg2RZScNNQUEXkqr1aCSdHVQsCR0bAMaUAVQTEZbgZlAL5Ecic qy4q7ofDNXeyu5Rl5euK/71y/Xl1jXqSdGGgoaaNOp8uOow1ktjVRytthJjEUS0EDANE zOBugJcm0tQlEcn+jVrpd1h7cudyXNnCCtQs6IXibzmft94d7r4espSilWNfNPZKTA7A uRrg== X-Forwarded-Encrypted: i=1; AJvYcCUHPQkGBIerAVTn6bkAPJVfz7LfBaYa8kDRF5g2hOihp6jKY2N0rwK2Bg17blF0sDk+ouhvrowualXAPPU=@vger.kernel.org X-Gm-Message-State: AOJu0Yx0PX4aa17HWhSg49Gh5BQc1Ws8yL/lp1gf6LvE0aDla4XnDZXF W2Jj/IFfMFY8b0YlTR7RQHWMAKuRrH5eCJ1vjZOD5m/pWXMnwmLQZeWy X-Gm-Gg: ATEYQzzECtsr4U6Dt1rv/7aKRG+JEEUcHTI4L4Jf1u87pl2JisbfQYDuKQcpU4HT1eQ ow2N/HoP64LwMYb1gQumB/Bs9tG3sFOyJHDTWlo/bV7/DYkwxlx4aw6z3sKjnCJ04AENPhqdKbt LgHsxAD7Sv3cbWdgpzzJnwUBLERLSwVNVuaVrhIGaByCjoG4g9x8XNap+a0U5jvVGea1YFEGwPK VarS544iSM4HE4xSG92n5bmLLYBlwObnUkqwV0l0140SQLnRyXDktFcKQa/9HCQwlR0KWQsAVVz iyXJwsN9f11oW4Cvza6UsWxmKENxwiIoKrvilxn+l+fgy5s6kOk3AX352FjZvdYLacpBBWvUNn1 fwh9oORUeUikJUGVkA0oTaQ8yxSvu0H5cM88e62A+tyjMhp/SxJBoRV7qmvFbX8Q6OT+SSlYmiZ AHU4SLLU1DETsk3u2KJiH4SMDue7x/9Ess X-Received: by 2002:a17:903:94b:b0:2ae:5a38:96bb with SMTP id d9443c01a7336-2b06357efd3mr61873795ad.2.1773816536783; Tue, 17 Mar 2026 23:48:56 -0700 (PDT) Received: from localhost.localdomain ([101.5.20.107]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b06e6315dcsm19262845ad.80.2026.03.17.23.48.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2026 23:48:55 -0700 (PDT) From: Qi Tang To: alibuda@linux.alibaba.com, dust.li@linux.alibaba.com, sidraya@linux.ibm.com, wenjia@linux.ibm.com Cc: netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Qi Tang Subject: [PATCH net] net/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer Date: Wed, 18 Mar 2026 14:48:47 +0800 Message-ID: <20260318064847.23341-1-tpluszz77@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" smc_rx_splice() allocates one smc_spd_priv per pipe_buffer and stores the pointer in pipe_buffer.private. The pipe_buf_operations for these buffers used .get =3D generic_pipe_buf_get, which only increments the page reference count when tee(2) duplicates a pipe buffer. The smc_spd_priv pointer itself was not handled, so after tee() both the original and the cloned pipe_buffer share the same smc_spd_priv *. When both pipes are subsequently released, smc_rx_pipe_buf_release() is called twice against the same object: 1st call: kfree(priv) sock_put(sk) smc_rx_update_cons() [correct] 2nd call: kfree(priv) sock_put(sk) smc_rx_update_cons() [UAF] KASAN reports a slab-use-after-free in smc_rx_pipe_buf_release(), which then escalates to a NULL-pointer dereference and kernel panic via smc_rx_update_consumer() when it chases the freed priv->smc pointer: BUG: KASAN: slab-use-after-free in smc_rx_pipe_buf_release+0x78/0x2a0 Read of size 8 at addr ffff888004a45740 by task smc_splice_tee_/74 Call Trace: dump_stack_lvl+0x53/0x70 print_report+0xce/0x650 kasan_report+0xc6/0x100 smc_rx_pipe_buf_release+0x78/0x2a0 free_pipe_info+0xd4/0x130 pipe_release+0x142/0x160 __fput+0x1c6/0x490 __x64_sys_close+0x4f/0x90 do_syscall_64+0xa6/0x1a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f BUG: kernel NULL pointer dereference, address: 0000000000000020 RIP: 0010:smc_rx_update_consumer+0x8d/0x350 Call Trace: smc_rx_pipe_buf_release+0x121/0x2a0 free_pipe_info+0xd4/0x130 pipe_release+0x142/0x160 __fput+0x1c6/0x490 __x64_sys_close+0x4f/0x90 do_syscall_64+0xa6/0x1a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Kernel panic - not syncing: Fatal exception Beyond the memory-safety problem, duplicating an SMC splice buffer is semantically questionable: smc_rx_update_cons() would advance the consumer cursor twice for the same data, corrupting receive-window accounting. A refcount on smc_spd_priv could fix the double-free, but the cursor-accounting issue would still need to be addressed separately. The .get callback is invoked by both tee(2) and splice_pipe_to_pipe() for partial transfers; both will now return -EFAULT. Users who need to duplicate SMC socket data must use a copy-based read path. Fixes: 9014db202cb7 ("smc: add support for splice()") Signed-off-by: Qi Tang --- net/smc/smc_rx.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/net/smc/smc_rx.c b/net/smc/smc_rx.c index d833e36f7fd4..c1d9b923938d 100644 --- a/net/smc/smc_rx.c +++ b/net/smc/smc_rx.c @@ -135,9 +135,16 @@ static void smc_rx_pipe_buf_release(struct pipe_inode_= info *pipe, sock_put(sk); } =20 +static bool smc_rx_pipe_buf_get(struct pipe_inode_info *pipe, + struct pipe_buffer *buf) +{ + /* smc_spd_priv in buf->private is not shareable; disallow cloning. */ + return false; +} + static const struct pipe_buf_operations smc_pipe_ops =3D { .release =3D smc_rx_pipe_buf_release, - .get =3D generic_pipe_buf_get + .get =3D smc_rx_pipe_buf_get, }; =20 static void smc_rx_spd_release(struct splice_pipe_desc *spd, --=20 2.43.0