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 3D5C938B15B; Sat, 12 Sep 2026 18:34:14 +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=1789238055; cv=none; b=NDGtv9sVNacsrOkKJODmcCkH43yeaZ6cS2PmfwD8e3xHzXLkHCvM9xypXGp6cNa+VZWmhuqmG7nFLq1NTlj8zaJ9+vfeAMyZexHbB7CEgI13AIff5p6WnUAso1MzZdJHEV1+akbU2AZVWs3ADawjnNPQImtYFgZrcQLHr7pnCBk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789238055; c=relaxed/simple; bh=btgOOYcgfZsz8WPW8LYvR40WgGR7kCGTSWbRifTzKmo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=f6zar6yIC57imos6LMO3VB/3fpREN2XK7O+3gdCMO7wNLdvFhlubQXH1hSbTZJTFZ+YgEpT/k+6h8KDmuex8rg6OBK72UzyfGS/MipibIpf19COaD3ZRVzaTcPVAwMgSbPTGdPhUblqO0h0jOAWvwMQrUq1aE7JJx0fLMg5Qpt4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=UDxju7Xk; 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="UDxju7Xk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A4601F000FF; Sat, 12 Sep 2026 18:34:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789238054; bh=7Yrli/LOyqpzDun+DpDWsy0EQ3LGOVt7+bFkxfguHn8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UDxju7XkQg3lWGlDmiDhswAQAi1PWF7uXqsqKZ+e9meUcVN+X/OPq4aAGkMnBncNU 6AMMSfxegmFWauPajq/fGBYG6kx/OVw4iPgCChBPyK52ykA+b6Z9qh17fBSK7ehVjE rxs+SAsoFXvRRc3PhGxLINUJjs9DUbEBvMhma6FA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Quan Sun <2022090917019@std.uestc.edu.cn>, Yinhao Hu , Kaiyan Mei , Dongliang Mu , Emil Tsalapatis , Jiayuan Chen , Martin KaFai Lau , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15 383/935] bpf: Fix same-register dst/src OOB read and pointer leak in sock_ops Date: Sat, 12 Sep 2026 08:56:53 +0200 Message-ID: <20260912065535.604629487@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065526.833703348@linuxfoundation.org> References: <20260912065526.833703348@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiayuan Chen [ Upstream commit 10f86a2a5c91fc4c4d001960f1c21abe52545ef6 ] When a BPF sock_ops program accesses ctx fields with dst_reg == src_reg, the SOCK_OPS_GET_SK() and SOCK_OPS_GET_FIELD() macros fail to zero the destination register in the !fullsock / !locked_tcp_sock path. Both macros borrow a temporary register to check is_fullsock / is_locked_tcp_sock when dst_reg == src_reg, because dst_reg holds the ctx pointer. When the check is false (e.g., TCP_NEW_SYN_RECV state with a request_sock), dst_reg should be zeroed but is not, leaving the stale ctx pointer: - SOCK_OPS_GET_SK: dst_reg retains the ctx pointer, passes NULL checks as PTR_TO_SOCKET_OR_NULL, and can be used as a bogus socket pointer, leading to stack-out-of-bounds access in helpers like bpf_skc_to_tcp6_sock(). - SOCK_OPS_GET_FIELD: dst_reg retains the ctx pointer which the verifier believes is a SCALAR_VALUE, leaking a kernel pointer. Fix both macros by: - Changing JMP_A(1) to JMP_A(2) in the fullsock path to skip the added instruction. - Adding BPF_MOV64_IMM(si->dst_reg, 0) after the temp register restore in the !fullsock path, placed after the restore because dst_reg == src_reg means we need src_reg intact to read ctx->temp. Fixes: fd09af010788 ("bpf: sock_ops ctx access may stomp registers in corner case") Fixes: 84f44df664e9 ("bpf: sock_ops sk access may stomp registers when dst_reg = src_reg") Reported-by: Quan Sun <2022090917019@std.uestc.edu.cn> Reported-by: Yinhao Hu Reported-by: Kaiyan Mei Reported-by: Dongliang Mu Reviewed-by: Emil Tsalapatis Closes: https://lore.kernel.org/bpf/6fe1243e-149b-4d3b-99c7-fcc9e2f75787@std.uestc.edu.cn/T/#u Signed-off-by: Jiayuan Chen Acked-by: Martin KaFai Lau Link: https://patch.msgid.link/20260407022720.162151-2-jiayuan.chen@linux.dev Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/core/filter.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 6c81daf9efc9d..f51e3940a2fe9 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -9723,10 +9723,11 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type, si->dst_reg, si->dst_reg, \ offsetof(OBJ, OBJ_FIELD)); \ if (si->dst_reg == si->src_reg) { \ - *insn++ = BPF_JMP_A(1); \ + *insn++ = BPF_JMP_A(2); \ *insn++ = BPF_LDX_MEM(BPF_DW, reg, si->src_reg, \ offsetof(struct bpf_sock_ops_kern, \ temp)); \ + *insn++ = BPF_MOV64_IMM(si->dst_reg, 0); \ } \ } while (0) @@ -9760,10 +9761,11 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type, si->dst_reg, si->src_reg, \ offsetof(struct bpf_sock_ops_kern, sk));\ if (si->dst_reg == si->src_reg) { \ - *insn++ = BPF_JMP_A(1); \ + *insn++ = BPF_JMP_A(2); \ *insn++ = BPF_LDX_MEM(BPF_DW, reg, si->src_reg, \ offsetof(struct bpf_sock_ops_kern, \ temp)); \ + *insn++ = BPF_MOV64_IMM(si->dst_reg, 0); \ } \ } while (0) -- 2.53.0