From nobody Mon Jun 8 21:47:55 2026 Received: from mail-m155101.qiye.163.com (mail-m155101.qiye.163.com [101.71.155.101]) (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 9BE652D6E58; Tue, 26 May 2026 13:15:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=101.71.155.101 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779801359; cv=none; b=XlENQfq7QtuHTFzIlk/vHmCADdXU3G8C6VzPlWFJEaAMQoSPFh1M4tsc/WSva/SSQJL5Fk6RLKbp1lIKNnk93W4dBSzvozYpb/NTNx1cgdlumEskLr9fYLcwt5N/KtzBOk6OAjMYrAdambSsKXzuw+t9dTjg3Suz2hmucOmwTkk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779801359; c=relaxed/simple; bh=A1PSrPrNwwaUJMqQUS+NB50LpwNS/5ZZxR9ytCWKvDQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=ALT0XGulhThF7AB3BFb6GAqMnDL0yv7QPYqKpcBPOEm0SJYiCnqdk8MaI9a9AWU+m8qfRY2bsZfAKhRT95o4QrErvMq3MbhscH8eRLzJt2I5d+yk6v7YEFXiLr0RR+C8C9hbBdA1wdFcI9fmAkUNmi2YY0UhrpIL/TtWuWgvttM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=seu.edu.cn; spf=pass smtp.mailfrom=seu.edu.cn; dkim=pass (1024-bit key) header.d=seu.edu.cn header.i=@seu.edu.cn header.b=CO6vrAB9; arc=none smtp.client-ip=101.71.155.101 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=seu.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=seu.edu.cn Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=seu.edu.cn header.i=@seu.edu.cn header.b="CO6vrAB9" Received: from DESKTOP-SUEFNF9.taila7e912.ts.net (unknown [223.112.146.162]) by smtp.qiye.163.com (Hmail) with ESMTP id 3fe349553; Tue, 26 May 2026 21:10:38 +0800 (GMT+08:00) From: Dawei Feng To: martin.lau@linux.dev Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, kees@kernel.org, joel.granados@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, jianhao.xu@seu.edu.cn, Dawei Feng , stable@vger.kernel.org, Zilin Guan Subject: [PATCH 1/2] bpf: cgroup: fix sysctl new value replacement Date: Tue, 26 May 2026 21:10:34 +0800 Message-Id: <20260526131035.1312864-2-dawei.feng@seu.edu.cn> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260526131035.1312864-1-dawei.feng@seu.edu.cn> References: <20260526131035.1312864-1-dawei.feng@seu.edu.cn> 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 X-HM-Tid: 0a9e64689ec103a2kunmbba6535a21ce X-HM-MType: 10 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFITzdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVkZHx9CVklNSU0eGUwdHkxLHVYeHw 5VEwETFhoSFyQUDg9ZV1kYEgtZQVlJSUhVSkpJVUpPTVVKTUlZV1kWGg8SFR0UWUFZT0tIVUpLSU hOQ0NVSktLVUtZBg++ DKIM-Signature: a=rsa-sha256; b=CO6vrAB96qBISTzUzV6TEjuj5CwDvqeENH+twONSu7upprtUbrmkhKyZyY17scfATFfgEhrggGWdF9dAMs6LBRZ/r+VPIU3MMLTelLgAa0nZwT10jxmRj1SA0m6jJtEgx1YromrNY8Mi1Vjl7RS+ocLxYh4BaaukYXHOtirQEv8=; c=relaxed/relaxed; s=default; d=seu.edu.cn; v=1; bh=DxSxRrpZGOEfgZWt6JDQ15rzmpa9lmoF54Zn8of9jIc=; h=date:mime-version:subject:message-id:from; Content-Type: text/plain; charset="utf-8" Commit 4e63acdff864 ("bpf: Introduce bpf_sysctl_{get,set}_new_value helpers") changed the success return value to 0, but failed to update the corresponding check in __cgroup_bpf_run_filter_sysctl(). Since bpf_prog_run_array_cg() now returns 0 on success, the legacy ret =3D=3D 1 condition is never satisfied. As a result, the modified value is ignored, and bpf_sysctl_set_new_value() fails to replace the write buffer. Fix this by checking for a return value of 0 instead, so cgroup/sysctl programs can correctly replace the pending sysctl buffer. This bug was discovered during a manual code review. Tested via a cgroup/sysctl BPF reproducer overriding writes to a target sysctl. Pre-fix, bpf_sysctl_set_new_value("foo") was silently ignored: the write returned 8192 and the value remained "600". Post-fix, the BPF replacement buffer properly propagates: the write returns 3 and the value updates to "foo". Fixes: 4e63acdff864 ("bpf: Introduce bpf_sysctl_{get,set}_new_value helpers= ") Cc: stable@vger.kernel.org Signed-off-by: Zilin Guan Signed-off-by: Dawei Feng --- kernel/bpf/cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index 876f6a81a9b6..8715a014c21d 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -1935,7 +1935,7 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_h= eader *head, =20 kfree(ctx.cur_val); =20 - if (ret =3D=3D 1 && ctx.new_updated) { + if (!ret && ctx.new_updated) { kfree(*buf); *buf =3D ctx.new_val; *pcount =3D ctx.new_len; --=20 2.34.1 From nobody Mon Jun 8 21:47:55 2026 Received: from mail-m49198.qiye.163.com (mail-m49198.qiye.163.com [45.254.49.198]) (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 6F0302C326F; Tue, 26 May 2026 13:15:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.254.49.198 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779801357; cv=none; b=Cd/e9+Xsi9oTO7ZKcmPOiG1/ErL/3j184jM6WTOZi5kXKUnqpXTU+vwWNvZr/N3SVsLusf8BlF5VUswMR7Lfww88hYCspJRoahqg1NfSoyViP8AhAMjgDKzqwpQy3N7O85CdaWEQXha53ucHs+PLXNTnfkMHfYkm749E0KKDi94= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779801357; c=relaxed/simple; bh=JHlqrdKCsBQwTg6MIVlG/v1fcP4xLqDplElkTbD1o1k=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=KZZzVQ05SXqrqTq6FQKwm6LPiFnlXiGubH4umxrb1KJiKNcLcAPSgBaE3hFXzywuFYUMnDPl7LoRcSBReRHyHEgu9qTk8JY4tEFtJUo88azCxgYdlhJutIS4DRzdMHLQ2Kx25v0Oc5f/Wy2MJM+y/+EFp3S9/4OIFkQuw7CeMbI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=seu.edu.cn; spf=pass smtp.mailfrom=seu.edu.cn; dkim=pass (1024-bit key) header.d=seu.edu.cn header.i=@seu.edu.cn header.b=J8v8cIba; arc=none smtp.client-ip=45.254.49.198 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=seu.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=seu.edu.cn Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=seu.edu.cn header.i=@seu.edu.cn header.b="J8v8cIba" Received: from DESKTOP-SUEFNF9.taila7e912.ts.net (unknown [223.112.146.162]) by smtp.qiye.163.com (Hmail) with ESMTP id 3fe349556; Tue, 26 May 2026 21:10:40 +0800 (GMT+08:00) From: Dawei Feng To: martin.lau@linux.dev Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, kees@kernel.org, joel.granados@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, jianhao.xu@seu.edu.cn, Dawei Feng , stable@vger.kernel.org, Zilin Guan Subject: [PATCH 2/2] bpf: cgroup: Use kvfree instead of kfree in __cgroup_bpf_run_filter_sysctl Date: Tue, 26 May 2026 21:10:35 +0800 Message-Id: <20260526131035.1312864-3-dawei.feng@seu.edu.cn> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260526131035.1312864-1-dawei.feng@seu.edu.cn> References: <20260526131035.1312864-1-dawei.feng@seu.edu.cn> 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 X-HM-Tid: 0a9e6468a7c203a2kunmbba6535a21d9 X-HM-MType: 10 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFITzdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVlDQx1LVh9MH0MZHh8fSE8eQ1YeHw 5VEwETFhoSFyQUDg9ZV1kYEgtZQVlJSUhVSkpJVUpPTVVKTUlZV1kWGg8SFR0UWUFZT0tIVUpLSU hOQ0NVSktLVUtZBg++ DKIM-Signature: a=rsa-sha256; b=J8v8cIbaJWgnNCPbspMLMraV8IjqYY1+srrlG7ggN3YBxkgo37Xmeo6eSenf2VSCfZrNWCam4SIa5/lg3PI8P3GadswaoHx8q78qXqc+P0d8RU0RyZRF9cqQRP0eFeOlOSX+7eWTGKvn6x0kyltB/6tmFeTOo2c0KoAhZC0vYQY=; c=relaxed/relaxed; s=default; d=seu.edu.cn; v=1; bh=rZAgge+PDHcPjQ2riIT+iKjy0DwpQ+PwemhCSwrlcjY=; h=date:mime-version:subject:message-id:from; Content-Type: text/plain; charset="utf-8" proc_sys_call_handler() allocates its temporary sysctl buffer with kvzalloc() and passes it to __cgroup_bpf_run_filter_sysctl(). Since kvzalloc() may fall back to vmalloc() for large allocations, freeing that buffer with kfree() is wrong and can corrupt memory. Use kvfree() to safely handle both kmalloc and kvzalloc()/vmalloc allocations. The bug was first flagged by an experimental analysis tool we are developing for kernel memory-management bugs while analyzing v6.13-rc1. The tool is still under development and is not yet publicly available. Manual inspection confirms that the bug is still present in v7.1-rc5. Reproduced the bug based on v7.1-rc4 in a QEMU x86_64 guest booted with KASAN and CONFIG_FAILSLAB enabled. The reproducer confines failslab injections to the proc_sys_call_handler() range, uses stacktrace-depth=3D32, and injects fail-nth=3D1 while writing 8191 bytes to /proc/sys/kernel/domainname from a task in the target cgroup. On the patch1-only kernel, fail-nth=3D1 triggered the fault: BUG: unable to handle page fault for address: ffffeb0200024d48 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 SMP KASAN NOPTI CPU: 2 UID: 0 PID: 209 Comm: repro_proc_sys_ Not tainted 7.1.0-rc4-00686-= g97625979a5d4 PREEMPT(lazy) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2= 014 RIP: 0010:kfree+0x6e/0x510 Code: 80 48 01 ef 0f 82 ae 04 00 00 48 c7 c0 00 00 00 80 48 2b 05 04 1b 2= 3 04 48 01 c7 48 c1 ef 0c 48 c1 e7 06 48 03 3d e2 1a 23 04 <4c> 8b 57 08 4c= 89 d0 83 e0 01 48 83 e8 01 49 09 c2 49 > RSP: 0018:ffff888108de7ab8 EFLAGS: 00010282 RAX: 0000777f80000000 RBX: ffff88815af398c0 RCX: 0000000000000080 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffeb0200024d40 RBP: ffffc90000935000 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff86b4b297 R11: 0000000000000000 R12: ffffffff819b71fd R13: 0000000000000001 R14: ffff888108de7cc0 R15: 0000000000000000 FS: 00007f8988cc2b80(0000) GS:ffff8881d3256000(0000) knlGS:0000000000000= 000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffeb0200024d48 CR3: 0000000101d6b000 CR4: 0000000000350ef0 Call Trace: ? __cgroup_bpf_run_filter_sysctl+0x626/0xc30 __cgroup_bpf_run_filter_sysctl+0x74d/0xc30 ? __pfx___cgroup_bpf_run_filter_sysctl+0x10/0x10 ? srso_return_thunk+0x5/0x5f ? __kvmalloc_node_noprof+0x345/0x870 ? proc_sys_call_handler+0x250/0x480 ? srso_return_thunk+0x5/0x5f proc_sys_call_handler+0x3a2/0x480 ? __pfx_proc_sys_call_handler+0x10/0x10 ? srso_return_thunk+0x5/0x5f ? selinux_file_permission+0x39f/0x500 ? srso_return_thunk+0x5/0x5f ? lock_is_held_type+0x9e/0x120 vfs_write+0x98e/0x1000 ? srso_return_thunk+0x5/0x5f ? kmem_cache_free+0x308/0x550 ? __pfx_vfs_write+0x10/0x10 ? __pfx_do_sys_openat2+0x10/0x10 ksys_write+0xf2/0x1d0 ? __pfx_ksys_write+0x10/0x10 ? srso_return_thunk+0x5/0x5f ? trace_irq_enable.constprop.0+0x110/0x140 do_syscall_64+0x115/0x690 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8988dd8907 Code: 10 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e = fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 = ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 > RSP: 002b:00007fff4069b878 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f8988dd8907 RDX: 0000000000001fff RSI: 0000564f97ef46b0 RDI: 0000000000000005 RBP: 0000564f97ef46b0 R08: 0000000000000000 R09: 0000564f97ef46b0 R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000001fff R14: 0000000000000005 R15: 0000000000000001 With this fix applied, rerunning the reproducer with the same fail-nth=3D1 setup yields no corresponding Oops reports. Fixes: 4508943794ef ("proc: use kvzalloc for our kernel buffer") Cc: stable@vger.kernel.org Signed-off-by: Zilin Guan Signed-off-by: Dawei Feng Reviewed-by: Emil Tsalapatis --- kernel/bpf/cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index 8715a014c21d..f4eefdacd453 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -1936,7 +1936,7 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_h= eader *head, kfree(ctx.cur_val); =20 if (!ret && ctx.new_updated) { - kfree(*buf); + kvfree(*buf); *buf =3D ctx.new_val; *pcount =3D ctx.new_len; } else { --=20 2.34.1