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 7C26351993C; Wed, 30 Sep 2026 17:26:41 +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=1790789202; cv=none; b=eyH/0CJcpe0dGVz29PmoVWjFgM4hAs3oQtMLXyEqV1IEY+FQzlPJkzrQ9jSRv3Mmm1h2vHzlG4GR+E4kyf0wSEHT+KBT7QEINI5ucqbt8GWcWBftANzpn06BBmq78RlrI6mNY7alOrfN0FJz4fk/qiH8HU4ZMPXInX5ITE8rOyI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790789202; c=relaxed/simple; bh=BZBbt1MABniEo+WvOwrClNpDlry5uHiczvOmEJoU6vs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=f2uWfWPi1jrgP4M7rBg3QCEZYMD9RyFY5YkDM548Gau1btlFkEDUKWjNqhxQ0BXvbjHoj788gvfPrszHghKPoCG+omEI1zNTF2WAEt+IYAEOT9hVhAMSpHo6+K/E0ArVqewry2R9yPxPyblum+KNBMDraD2Wep9VRBFklc7xGUY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=J4siYzHC; 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="J4siYzHC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3E8B1F000FF; Wed, 30 Sep 2026 17:26:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790789201; bh=ZqO97dXsZLsJFtfFWE6NuA+JIPIUY1zxqXcfl1ziw+M=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=J4siYzHCwf4B4lZpiNvjTWILB5ezJHLVv6Cwv24R2i30ats0WMJpW0zc8wIDJUzLR 33JFobOUs0+N66L5VRR4eEQp8YjkHWWdjDwdSmSKFijcCUEasSFPFxtF7MMGQsNMQo 9XUGL21NSWeYiuY44Nhb99CZYv0QA7FOaMXvlKGk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zhao Gongyi , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.12 392/877] bpf, sockmap: Reject max_entries > INT_MAX in sock_map_alloc Date: Wed, 30 Sep 2026 17:21:43 +0200 Message-ID: <20260930152423.143674013@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152414.738996857@linuxfoundation.org> References: <20260930152414.738996857@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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zhao Gongyi [ Upstream commit 814a81c842bd88f6bd8a4ce550d560df071a5d03 ] sock_map_alloc() only rejects max_entries == 0 and otherwise allows any u32 value. sock_map_free() then walks the sks[] array with a signed int iterator: int i; for (i = 0; i < stab->map.max_entries; i++) struct sock **psk = &stab->sks[i]; When a SOCKMAP is created with max_entries = 0xffffffff (UINT_MAX), the allocation of 32 GiB can succeed on large-memory hosts. During free the counter reaches 0x80000000, wraps to INT_MIN, is sign-extended by movslq and turned into a ~16 GiB negative offset from stab->sks, pointing far below the allocation. The faulting access is an xchg() write in sock_map_free(). Without KASAN, the same out-of-bounds write can fault on an unmapped vmalloc page or corrupt an unrelated allocation if that vmalloc address is populated. On a KASAN kernel with CONFIG_KASAN_VMALLOC=y, the shadow check for that address hits an unmapped shadow page and oopses first: BUG: unable to handle page fault for address: fffff521b59c5a00 RIP: 0010:kasan_check_range+0x107/0x190 Call Trace: sock_map_free+0x93/0x190 map_create+0x68d/0xb30 __sys_bpf+0x21e/0x2e70 Vmcore confirmed stab->map.max_entries == 0xffffffff, stab->sks == 0xffffc911ace2d000, and the faulting address sks + (s64)INT_MIN * 8 exactly at 0xffffc90dace2d000. The same buggy path is reached on the normal close()/bpf_map_free_deferred() path whenever such a map is destroyed. sock_map_alloc() used to bound its allocation size through bpf_map_charge_init(), but the bound was dropped when rlimit-based memory accounting was removed. Reject max_entries > INT_MAX at creation time so the signed iterator in sock_map_free() never sees a value that would overflow. Triggered by syzkaller and reproduced on both a 6.6-based KASAN kernel and the upstream v7.3-rc2 kernel. Fixes: 0d2c4f964050 ("bpf: Eliminate rlimit-based memory accounting for sockmap and sockhash maps") Signed-off-by: Zhao Gongyi Signed-off-by: Alexei Starovoitov Link: https://patch.msgid.link/20260917121016.48171-1-zhaogongyi@bytedance.com Signed-off-by: Sasha Levin --- net/core/sock_map.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 6440ce16fc621..be4a4f8f346cb 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -41,6 +41,7 @@ static struct bpf_map *sock_map_alloc(union bpf_attr *attr) struct bpf_stab *stab; if (attr->max_entries == 0 || + attr->max_entries > INT_MAX || attr->key_size != 4 || (attr->value_size != sizeof(u32) && attr->value_size != sizeof(u64)) || -- 2.53.0