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 AD6B64A3F25 for ; Thu, 10 Sep 2026 15:44:48 +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=1789055089; cv=none; b=DMqs1e1VSp6Ay+jA3L/HpwufW/EFMInCSqCItijvw14P8thSlz5LeKW3kycwoKoWshLcIcWI43kHwegjITxlBUar3DOXITrBt1m2yckM6egvMd2IhTNP2TJElpy0xVdBwUltgSmTIrPyTCeMKJm8P8eMo5ETFqeoYGr+JT9eoNo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789055089; c=relaxed/simple; bh=gp2RoKk+MBhaSAs3n0MBgUyA9gjGA4o9L39proy2iMY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oqVz8X3F1nSeEYp5mztfZ29Q1FgmycMree5ejjRB9zsWw/36T3rCHOEr4ctOyebuEf3Uv9Zhcy4GsWZe9K48Y2DDsEpsdXskbQauCbShMwIXvVBLi4vFQBm1EWRWxBjIgh+VbLmU+ZbPqCkvV+t9ONpnuPqKP7ZFZFcLaNWhtVM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QQduFc1g; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="QQduFc1g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 115BC1F00893; Thu, 10 Sep 2026 15:44:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789055088; bh=x+P3BUlE/ZjR8LEph9Mlhbrq0YuFiixgNmIduHjVpyw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=QQduFc1gv78FZ54bm4geRNJUCqeQqX42QDmk65TTpJY/gzAIpyoZTVtdd13NPCyDI 7gwQyNvq5V1k82H81J/EqGaIDPBL8Y/4NndcjSk4rHiS2YiTSpOgkMrWo9qLsq0Ip+ YkPbuLmF5zADVjNKpjPqR9zwqtfNW2/nSP5hJHkj1xw7ghW6h2UvZcZxVMFEQcTaz6 Q5dr69ugsB0w0aTmABAst3SaSWfkapDW044cnAIP+jdYtbWfEDSI2ck6Dig7VAJrnw MXbk8AAbcutFBCDRJWU965f1OpC2dtMRAqC3ZY7Amn93v3/dmhrFVT6U/CUvDbtSdH CHV2yYqeKKrlw== From: Sasha Levin To: stable@vger.kernel.org Cc: "Masami Hiramatsu (Google)" , Sashiko , Sasha Levin Subject: [PATCH 5.10.y] kprobes: Protect kprobe_blacklist with RCU Date: Thu, 10 Sep 2026 11:44:46 -0400 Message-ID: <20260910154446.1032841-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090833-slinging-thesis-77c0@gregkh> References: <2026090833-slinging-thesis-77c0@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Masami Hiramatsu (Google)" [ Upstream commit 0c4256196b3a105307e2235fbfd85e768bbcdd0f ] __within_kprobe_blacklist() traverses kprobe_blacklist without holding kprobe_mutex. When a module is unloaded, kprobe_remove_area_blacklist() removes blacklist entries and immediately frees them with kfree(). A concurrent call to within_kprobe_blacklist() can therefore dereference freed memory. Furthermore, within_kprobe_blacklist() can be called in atomic or non-preemptible contexts where the sleeping kprobe_mutex cannot be taken. Protect kprobe_blacklist with RCU. Use guard(rcu)() and list_for_each_entry_rcu() for traversal, list_add_tail_rcu() for insertions, list_del_rcu() for deletions, and kfree_rcu() to reclaim entries safely after a grace period. Link: https://lore.kernel.org/all/178810004323.64882.16493230858653316962.stgit@devnote2/ Fixes: 376e242429bf ("kprobes: Introduce NOKPROBE_SYMBOL() macro to maintain kprobes blacklist") Cc: stable@vger.kernel.org Reported-by: Sashiko Closes: https://lore.kernel.org/all/20260807155802.F06041F000E9@smtp.kernel.org/ Assisted-by: Antigravity:gemini-3.7-flash Signed-off-by: Masami Hiramatsu (Google) [ Replaced guard(rcu)() with explicit rcu_read_lock()/rcu_read_unlock() to avoid declaration-after-statement warnings. ] Signed-off-by: Sasha Levin --- include/linux/kprobes.h | 1 + kernel/kprobes.c | 19 ++++++++++++++----- 2 files changed, 15 insertions(+), 5 deletions(-) diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 18b7c40ffb37a..71b15c923077e 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -178,6 +178,7 @@ struct kprobe_blacklist_entry { struct list_head list; unsigned long start_addr; unsigned long end_addr; + struct rcu_head rcu; }; #ifdef CONFIG_KPROBES diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 551ac118159f9..46398072b5bea 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1513,11 +1513,20 @@ static bool __within_kprobe_blacklist(unsigned long addr) /* * If there exists a kprobe_blacklist, verify and * fail any probe registration in the prohibited area + * Note: this can return true during transition period where + * (start_addr, end_addr) in the black list is shrinking + * but old entry has not been removed yet. This is acceptable + * because the worst case is that we reject more probes than + * we should. */ - list_for_each_entry(ent, &kprobe_blacklist, list) { - if (addr >= ent->start_addr && addr < ent->end_addr) + rcu_read_lock(); + list_for_each_entry_rcu(ent, &kprobe_blacklist, list) { + if (addr >= ent->start_addr && addr < ent->end_addr) { + rcu_read_unlock(); return true; + } } + rcu_read_unlock(); return false; } @@ -2388,7 +2397,7 @@ int kprobe_add_ksym_blacklist(unsigned long entry) ent->start_addr = entry; ent->end_addr = entry + size; INIT_LIST_HEAD(&ent->list); - list_add_tail(&ent->list, &kprobe_blacklist); + list_add_tail_rcu(&ent->list, &kprobe_blacklist); return (int)size; } @@ -2417,8 +2426,8 @@ static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end) list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) { if (ent->start_addr < start || ent->start_addr >= end) continue; - list_del(&ent->list); - kfree(ent); + list_del_rcu(&ent->list); + kfree_rcu(ent, rcu); } } -- 2.53.0