From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.3]) (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 8BBE71922FD; Fri, 25 Sep 2026 04:35:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.3 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790310955; cv=none; b=jOtSZoFLSS6B/aUYFpgW6ZfTw/bORnwgFHSzGcUkVJX+HpPMduJY9Mk+Ye+dvedlq09peK9wMaZ4W0AogY0tZEqPEDUOqbLvJYxnSDsmImDovrRQYFwdkfPu53FvkJTew4L8yGqZ6FQecBRr51+XOMuDSUJeV8nFoMCIF/I3Gug= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790310955; c=relaxed/simple; bh=5R/00RgV2CHP3vBjYoIYpHO3TakxBiNZ9JgtvqzTPYs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RxPGde7a/SAH7+fLhHSkUPDGq7x4G+YKJv1cKEb6nvUFi8v4DLU1/hteEFJbs4lwqDxh9crmrGjReAHyVXEz2y94VxuF0tsZFoz7/JqWQu/ZOkio+GylxEDlFwQqx5X8c8Q/QwZZEGhi7n4X678gpDiwPBx8R/R7iaZCJ3We1Us= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=YpcBVlKO; arc=none smtp.client-ip=220.197.31.3 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="YpcBVlKO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=6S R9jQCvbn4qzh5twTIN9Zz5Q8q2WS36fgkLBJ4vwO8=; b=YpcBVlKODdBzwDoVR8 qFub1QQg+cUqq/0janXB6ENoO84mV5FWbHtOh3LxUEA8xoVrTn7VMItHSYj0uk1q +KZ/MFMu3RrtiJpBILnxzIrSV42Z4qpCf8iSieFwMNX4PQtJvTgJbZriWdNphPuO oh/fv4AHGhETjWyKvxXl3JBQo= Received: from nec8-i7 (unknown []) by gzga-smtp-mtada-g1-2 (Coremail) with SMTP id _____wD3__T7+bVqQ0LEAg--.64744S2; Fri, 25 Sep 2026 12:35:09 +0800 (CST) From: chenyuan_fl@163.com To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, jolsa@kernel.org, leon.hwang@linux.dev, linux-kernel@vger.kernel.org, Yuan Chen Subject: [PATCH bpf-next] bpf: Roll back freplace link state when bpf_arch_text_poke() fails Date: Fri, 25 Sep 2026 12:35:00 +0800 Message-ID: <20260925043500.28030-1-chenyuan_fl@163.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <4669addf.91e8.1a0d2da9b9c.Coremail.chenyuan_fl@163.com> References: <4669addf.91e8.1a0d2da9b9c.Coremail.chenyuan_fl@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wD3__T7+bVqQ0LEAg--.64744S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7uF47WF4xZryfJw4Duw1ftFb_yoW8Aw45pF y7JF9xCr4DX34qq34vvw18WFWY93WkWw4xGrWjg397CFs3XrZ5Wry0gwnIvFyFgrs5u3WI qF4a9rn09r17WFDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jn8n5UUUUU= X-CM-SenderInfo: xfkh05pxdqswro6rljoofrz/xtbDAh3Fg2q1+f3OaAAA3k From: Yuan Chen A freplace attach claims the target prog by bumping tgt_prog->aux->freplace_link_cnt and setting tr->extension_prog. bpf_arch_text_poke() then makes the extension take effect. If the poke fails, the claims are never released: the attach unwinds through bpf_link_cleanup(), which clears link->prog, so bpf_trampoline_unlink_prog() never runs. Drop the link count under ext_mutex on the error path, and set tr->extension_prog only after the poke succeeded. The count is still bumped before the poke: it blocks prog_array updates while the entry is patched. Fixes: d6083f040d5d ("bpf: Prevent tailcall infinite loop caused by freplace") Suggested-by: Leon Hwang Signed-off-by: Yuan Chen --- kernel/bpf/trampoline.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index da85bd580ef0..bf4ab0ac264e 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -973,10 +973,17 @@ static int __bpf_trampoline_link_prog(struct bpf_tramp_node *node, err = bpf_freplace_link_tgt_prog(tgt_prog); if (err) return err; + err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_NOP, + BPF_MOD_JUMP, NULL, + node->link->prog->bpf_func); + if (err) { + /* Undo the claim from bpf_freplace_link_tgt_prog(). */ + guard(mutex)(&tgt_prog->aux->ext_mutex); + tgt_prog->aux->freplace_link_cnt--; + return err; + } tr->extension_prog = node->link->prog; - return bpf_arch_text_poke(tr->func.addr, BPF_MOD_NOP, - BPF_MOD_JUMP, NULL, - node->link->prog->bpf_func); + return 0; } err = bpf_trampoline_add_prog(tr, node, cnt); if (err) -- 2.54.0