From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-fw-6002.amazon.com (smtp-fw-6002.amazon.com [52.95.49.90]) (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 B742213A3EC for ; Thu, 14 Nov 2024 10:34:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.95.49.90 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731580470; cv=none; b=nPsQt7p+pwMjpSYAtKizvqq+vZ/9Nx+yXMCojv16KCvO7XhQxDpDOus39iFzhun4OlpTJa/wQf+h2XHuOSRhXhPynFuHFHXb0emeE9oq/YLDUct1Unrcw8tsimbzPWayALUh04pFzz/0Mme6aylXrOHS+TvAcFKJn3uXJBvsg3g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731580470; c=relaxed/simple; bh=W6bHKOTQHw2lZoEIxafwIaRnd0+k/G1N2zyEqGkdMMA=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=P3NUp/mLzz60Hpc/42x92sB1V+R0bTDh1kFg1F8riRc+qcEWG+FkkBW8EvzNtsFZOstJRyDkPJFzOlHB5pNUrYdRGV7e0BVulFpMBRO1VAudbgGqfjr3KReMj8z4liKNeBOsqVG85bXXKdLb+kf7ABuya84U4mkmOW5pJmtL94Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.com; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=v/HytQ9L; arc=none smtp.client-ip=52.95.49.90 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="v/HytQ9L" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1731580469; x=1763116469; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=dBlUcW8QG6yN1LEvwuqZSZu1m0lG4SBYm75VKnj/Lj0=; b=v/HytQ9LnSXkc5wbhG1bzd2OnnVBDpRUtEJnbajiop9f4kXNFuFH70Fp TYuyn6dmCxpEP0rzgZIJ4oIB/ayYXYRZ761vn2EyAFpoZgnftetFil+5D KRIlTarnu8FrWB6/s17jaCW43Shnle/CTUQ8W2N9nW4oII6YIqCoP2BLx 4=; X-IronPort-AV: E=Sophos;i="6.12,153,1728950400"; d="scan'208";a="448880841" Received: from iad6-co-svc-p1-lb1-vlan3.amazon.com (HELO smtpout.prod.us-east-1.prod.farcaster.email.amazon.dev) ([10.124.125.6]) by smtp-border-fw-6002.iad6.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Nov 2024 10:34:28 +0000 Received: from EX19MTAUEA001.ant.amazon.com [10.0.29.78:46957] by smtpin.naws.us-east-1.prod.farcaster.email.amazon.dev [10.0.15.229:2525] with esmtp (Farcaster) id e5a500e2-c23c-42a3-afdc-069fad8560ea; Thu, 14 Nov 2024 10:34:27 +0000 (UTC) X-Farcaster-Flow-ID: e5a500e2-c23c-42a3-afdc-069fad8560ea Received: from EX19EXOUEC001.ant.amazon.com (10.252.135.173) by EX19MTAUEA001.ant.amazon.com (10.252.134.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34; Thu, 14 Nov 2024 10:34:27 +0000 Received: from EX19MTAUEB001.ant.amazon.com (10.252.135.35) by EX19EXOUEC001.ant.amazon.com (10.252.135.173) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34; Thu, 14 Nov 2024 10:34:26 +0000 Received: from email-imr-corp-prod-pdx-all-2b-22fa938e.us-west-2.amazon.com (10.124.125.2) by mail-relay.amazon.com (10.252.135.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34 via Frontend Transport; Thu, 14 Nov 2024 10:34:26 +0000 Received: from dev-dsk-hagarhem-1b-b868d8d5.eu-west-1.amazon.com (dev-dsk-hagarhem-1b-b868d8d5.eu-west-1.amazon.com [10.253.65.58]) by email-imr-corp-prod-pdx-all-2b-22fa938e.us-west-2.amazon.com (Postfix) with ESMTP id EAF03C04D7; Thu, 14 Nov 2024 10:34:25 +0000 (UTC) Received: by dev-dsk-hagarhem-1b-b868d8d5.eu-west-1.amazon.com (Postfix, from userid 23002382) id 8145D224F4; Thu, 14 Nov 2024 10:34:25 +0000 (UTC) From: Hagar Hemdan To: CC: , Zheng Yejian , , , , Steven Rostedt , Hagar Hemdan Subject: [PATCH 5.4 v2] ftrace: Fix possible use-after-free issue in ftrace_location() Date: Thu, 14 Nov 2024 10:33:59 +0000 Message-ID: <20241114103359.31275-1-hagarhem@amazon.com> X-Mailer: git-send-email 2.40.1 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain From: Zheng Yejian commit e60b613df8b6253def41215402f72986fee3fc8d upstream. KASAN reports a bug: BUG: KASAN: use-after-free in ftrace_location+0x90/0x120 Read of size 8 at addr ffff888141d40010 by task insmod/424 CPU: 8 PID: 424 Comm: insmod Tainted: G W 6.9.0-rc2+ [...] Call Trace: dump_stack_lvl+0x68/0xa0 print_report+0xcf/0x610 kasan_report+0xb5/0xe0 ftrace_location+0x90/0x120 register_kprobe+0x14b/0xa40 kprobe_init+0x2d/0xff0 [kprobe_example] do_one_initcall+0x8f/0x2d0 do_init_module+0x13a/0x3c0 load_module+0x3082/0x33d0 init_module_from_file+0xd2/0x130 __x64_sys_finit_module+0x306/0x440 do_syscall_64+0x68/0x140 entry_SYSCALL_64_after_hwframe+0x71/0x79 The root cause is that, in ftrace_location_range(), ftrace record of some address is being searched in ftrace pages of some module, but those ftrace pages at the same time is being freed in ftrace_release_mod() as the corresponding module is being deleted: CPU1 | CPU2 register_kprobes() { | delete_module() { check_kprobe_address_safe() { | arch_check_ftrace_location() { | ftrace_location() { | lookup_rec() // USE! | ftrace_release_mod() // Free! To fix this issue: 1. Hold rcu lock as accessing ftrace pages in ftrace_location_range(); 2. Use ftrace_location_range() instead of lookup_rec() in ftrace_location(); 3. Call synchronize_rcu() before freeing any ftrace pages both in ftrace_process_locs()/ftrace_release_mod()/ftrace_free_mem(). Link: https://lore.kernel.org/linux-trace-kernel/20240509192859.1273558-1-zhengyejian1@huawei.com Cc: stable@vger.kernel.org Cc: Cc: Cc: Fixes: ae6aa16fdc16 ("kprobes: introduce ftrace based optimization") Suggested-by: Steven Rostedt Signed-off-by: Zheng Yejian Signed-off-by: Steven Rostedt (Google) [Hagar: Modified to apply on v5.4.y] Signed-off-by: Hagar Hemdan --- V1: https://lore.kernel.org/all/20241111144445.27428-1-hagarhem@amazon.com/ Changes in V2 - fix coding style - tested before and after patch applied, no new failures --- kernel/trace/ftrace.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 412505d94865..648b8677f71b 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1552,7 +1552,9 @@ unsigned long ftrace_location_range(unsigned long start, unsigned long end) struct ftrace_page *pg; struct dyn_ftrace *rec; struct dyn_ftrace key; + unsigned long ip = 0; + rcu_read_lock(); key.ip = start; key.flags = end; /* overload flags, as it is unsigned long */ @@ -1564,11 +1566,13 @@ unsigned long ftrace_location_range(unsigned long start, unsigned long end) rec = bsearch(&key, pg->records, pg->index, sizeof(struct dyn_ftrace), ftrace_cmp_recs); - if (rec) - return rec->ip; + if (rec) { + ip = rec->ip; + break; + } } - - return 0; + rcu_read_unlock(); + return ip; } /** @@ -5736,6 +5740,8 @@ static int ftrace_process_locs(struct module *mod, /* We should have used all pages unless we skipped some */ if (pg_unuse) { WARN_ON(!skipped); + /* Need to synchronize with ftrace_location_range() */ + synchronize_rcu(); ftrace_free_pages(pg_unuse); } return ret; @@ -5889,6 +5895,9 @@ void ftrace_release_mod(struct module *mod) out_unlock: mutex_unlock(&ftrace_lock); + /* Need to synchronize with ftrace_location_range() */ + if (tmp_page) + synchronize_rcu(); for (pg = tmp_page; pg; pg = tmp_page) { /* Needs to be called outside of ftrace_lock */ @@ -6196,6 +6205,7 @@ void ftrace_free_mem(struct module *mod, void *start_ptr, void *end_ptr) unsigned long start = (unsigned long)(start_ptr); unsigned long end = (unsigned long)(end_ptr); struct ftrace_page **last_pg = &ftrace_pages_start; + struct ftrace_page *tmp_page = NULL; struct ftrace_page *pg; struct dyn_ftrace *rec; struct dyn_ftrace key; @@ -6239,12 +6249,8 @@ void ftrace_free_mem(struct module *mod, void *start_ptr, void *end_ptr) ftrace_update_tot_cnt--; if (!pg->index) { *last_pg = pg->next; - if (pg->records) { - free_pages((unsigned long)pg->records, pg->order); - ftrace_number_of_pages -= 1 << pg->order; - } - ftrace_number_of_groups--; - kfree(pg); + pg->next = tmp_page; + tmp_page = pg; pg = container_of(last_pg, struct ftrace_page, next); if (!(*last_pg)) ftrace_pages = pg; @@ -6261,6 +6267,11 @@ void ftrace_free_mem(struct module *mod, void *start_ptr, void *end_ptr) clear_func_from_hashes(func); kfree(func); } + /* Need to synchronize with ftrace_location_range() */ + if (tmp_page) { + synchronize_rcu(); + ftrace_free_pages(tmp_page); + } } void __init ftrace_free_init_mem(void) -- 2.40.1