From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793210415; b=ipSjHDw4XgI+NsbUZ8gtbwylJQfvCEznYy0AlSFkn1RAEGyorr1QmCS0n+q87a9qq9mR B9PnwApSmjedWCwuxmxKdMXOgO/QH3JiEAjgMqUcNNeKj2u2Wq/lUd1M6NS04jq6+BYqh R9HHz9Up1Qyzt8uIxsG40J6ZoHGFWtTHxCGJKnhv3p/qVqIYNuRzzwwlxHVDjQe5bD4i+ hIj1E0JBBpZJneAzqIpYpVn6xZXyJNkFrXSHR2dwCG6zybSgXTYYHoHew91Ojlx43v0Y0 GVy1AZ4y2jPyEvS6r2uoXzx//0IgELL91LPLPoeH7C5hGbhKYIIjcwiuqMjSygOckMg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793210415; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=tsKVYN1MmHIeps29r+mk19fcWySjCoLQZJVUqiDuSfI=; b=TZCtzfGg3W9kEpBlIEaE6xDQ0oxY+BJSjWb8XU2MlBGWaTBNrwM9j0IG80VQs/Bryxzo BGgUFDqQtsnDzikKlvbxFIa9e9WehXhqY907sJ28MX11um4i02TtLkE2lXP6vuRpFQ+6a 4yCVD0HdzjMWJcirYxcseWdbe050N3ye//kzMpa7sQCsgDGxdDKMtzInPCdNioZtZclt/ TZY+pFUDhJVXD1/pQbSo6pKwbKU8xEpgLez1uVsE5O0NsNkGaG7lji/fsJDAnKYoeanIJ Aa/ItH+Kh5QB4b6sVoMvXVJpqrK6/zhuhvsa4TgYcOVMySny1dfDcJjRLmtZ4R6/NoA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=vid57C84; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 32F03606A31D; Wed, 28 Oct 2026 18:00:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=vid57C84 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7EABB1F01828; Wed, 28 Oct 2026 18:00:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793210415; bh=tsKVYN1MmHIeps29r+mk19fcWySjCoLQZJVUqiDuSfI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=vid57C842iGQTAW9WtxcJCel9O7vk9YMqELC3SWp0X5zx9/OSenUth60rwaPeJYIo LlXEnpv5wrS/1atWTrUy7QQfp4z90wLyiIjej5PpcYQw/Q4EdX5q/0ckGaT2RRZ6MJ 5bbFHPGbXW+U+t++mE671F1wdSY8TNs2bhA0aF70= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sashiko , "Masami Hiramatsu (Google)" , Sasha Levin Subject: [PATCH 5.15 019/571] kprobes: Protect kprobe_blacklist with RCU Date: Wed, 28 Oct 2026 17:52:46 +0100 Message-ID: <20261028170008.478172105@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ 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 24b0eaa5de307..e5262feff8267 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -177,6 +177,7 @@ 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 0d463859ad329..69d166f42d04a 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1427,11 +1427,20 @@ 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; } @@ -2258,7 +2267,7 @@ 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; } @@ -2287,8 +2296,8 @@ 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