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 878EA367B92; Tue, 21 Jul 2026 22:39:27 +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=1784673568; cv=none; b=K7uH61OQBcGv+C2isD7LT7GH4zJ1ED+BdsQ99TeCTj4f0Xf9E+wHj3+7WI5mJuW/CMRSxnT/LOB/es00zEF8Vcl7goMXnOfgXIeD79ct3WkxOZciGA/LxNxqFsU28Akntmv02aOhIH7j2s7lxniWFBTY7j5Wr0KtrLhdLkHueV4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784673568; c=relaxed/simple; bh=SvZMRD9/xyOTnARUMdUh+O9uogHnfIWimY2OYVksZV4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PXhgMB5P3NtUllQu0jWjqtHoSX1ceHWxaPRODcpOM0JXsnrX7Aa8h5kp1lBwL1LHdXzWyM+mbQ0WFI8rkInMHqkRDxB0jFr/7TDtDhIh3haTiFAs2OrU4770DXrDr/ASceESycETAg88ZB7gGJAPuW1N9y+2vvlgZnGOYBDLEno= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0d1NHupV; 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="0d1NHupV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD84F1F000E9; Tue, 21 Jul 2026 22:39:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784673567; bh=lOWPfx4beBpeNJcqqk3++YzPCt386MRbMuESozqfj+s=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=0d1NHupVBhpt+9k7f970JBgLpgpJgRCWv0ssmXz1sR9L4vc/6VoGBbB8JchCtUlF7 WiCIulrBs+70hrqMXlgbO8wbUIjTCrI0QCDB1kVvc6ExBl6A1vJZEm74T5/487KZtZ T1owAmNU/1awJHvdVXMk7rSQac1PeU05ZN3SwKlM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jakub Kicinski , Jiayuan Chen , Sasha Levin Subject: [PATCH 5.10 210/699] net/sched: cls_bpf: prevent unbounded recursion in offload rollback Date: Tue, 21 Jul 2026 17:19:29 +0200 Message-ID: <20260721152400.436277526@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152355.667394603@linuxfoundation.org> References: <20260721152355.667394603@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 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiayuan Chen [ Upstream commit 27db54b90bcc7c37867fe664107fa25ea6a116e4 ] Quan Sun reported [1] a stack overflow in cls_bpf_offload_cmd(). Reproducer on netdevsim: add a skip_sw cls_bpf filter, set the bpf_tc_accept debugfs knob to 0, then `tc filter replace`. The replace calls tc_setup_cb_replace() which fails. cls_bpf_offload_cmd() then swaps prog/oldprog and recursively calls itself to roll back. But bpf_tc_accept=0 makes the rollback fail too, which triggers yet another rollback frame with the same arguments, and so on until the stack is exhausted. bpf_tc_accept is just a convenient knob for the reproducer. Any driver whose tc_setup_cb_replace() fails twice in a row can hit the same loop, so this is not a netdevsim-only issue. Two ways to fix it: 1) Have the rollback call tc_setup_cb_add() on oldprog instead of re-entering cls_bpf_offload_cmd(). 2) Mark the rollback frame with a flag and skip a second-level rollback from inside it. Go with (2). It is the smaller change and keeps the original behaviour: the rollback still goes through tc_setup_cb_replace(), so the driver gets one real chance to restore its state. If that attempt also fails, we just return the original error instead of recursing. [1]: https://lore.kernel.org/bpf/ce5a6005-3c5e-4696-9e05-eba9461dc860@std.uestc.edu.cn/T/#u Fixes: 102740bd9436 ("cls_bpf: fix offload assumptions after callback conversion") Reviewed-by: Jakub Kicinski Signed-off-by: Jiayuan Chen Link: https://patch.msgid.link/20260526025529.24382-1-jiayuan.chen@linux.dev Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/cls_bpf.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c index 6e3e63db0e0168..70bb1482c8736e 100644 --- a/net/sched/cls_bpf.c +++ b/net/sched/cls_bpf.c @@ -143,7 +143,8 @@ static bool cls_bpf_is_ebpf(const struct cls_bpf_prog *prog) static int cls_bpf_offload_cmd(struct tcf_proto *tp, struct cls_bpf_prog *prog, struct cls_bpf_prog *oldprog, - struct netlink_ext_ack *extack) + struct netlink_ext_ack *extack, + bool is_rollback) { struct tcf_block *block = tp->chain->block; struct tc_cls_bpf_offload cls_bpf = {}; @@ -178,7 +179,8 @@ static int cls_bpf_offload_cmd(struct tcf_proto *tp, struct cls_bpf_prog *prog, &oldprog->in_hw_count, true); if (prog && err) { - cls_bpf_offload_cmd(tp, oldprog, prog, extack); + if (!is_rollback) + cls_bpf_offload_cmd(tp, oldprog, prog, extack, true); return err; } @@ -209,7 +211,7 @@ static int cls_bpf_offload(struct tcf_proto *tp, struct cls_bpf_prog *prog, if (!prog && !oldprog) return 0; - return cls_bpf_offload_cmd(tp, prog, oldprog, extack); + return cls_bpf_offload_cmd(tp, prog, oldprog, extack, false); } static void cls_bpf_stop_offload(struct tcf_proto *tp, @@ -218,7 +220,7 @@ static void cls_bpf_stop_offload(struct tcf_proto *tp, { int err; - err = cls_bpf_offload_cmd(tp, NULL, prog, extack); + err = cls_bpf_offload_cmd(tp, NULL, prog, extack, false); if (err) pr_err("Stopping hardware offload failed: %d\n", err); } -- 2.53.0