From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from plesk.hostmyservers.fr (plesk.hostmyservers.fr [45.145.164.37]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3AC76352FFF; Fri, 5 Sep 2025 13:48:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.145.164.37 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757080122; cv=none; b=DOdGaiMhixhLr2Uw/QTKFxP2AUsIYgok0xOXCVYESxVmPMoiWyZBZPOzmJH8WIvJBkF+Bm9XRXsNM8w4rRDl07BuRnBgj+X725mV7rJqrPQyFvyxNqDhUYnQfF4ZfAOoNxmUCRqWpFffeyprsL8F2jruVTCDeAuBB2UHeKBj/Cs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757080122; c=relaxed/simple; bh=znhd37DdN6KALLrsCH/O6IMvCVPXC7uRg/8pj3Fasqc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=VtVRuYqE519gZFN70rUi9KxaO0XKxX+oMgZ+U+asQNTVxgQDC8Gd2sttEMQPBAP/i6+FmaPsHXIz48V9In5v5DGAusVDHT40p5A4SAVN3Lqfkm35knp3bELXOvj5vF7pUUlE+DIc79vhlCPMllNJwOTaSQCVzFCbIxsfEtOneS4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=arnaud-lcm.com; spf=pass smtp.mailfrom=arnaud-lcm.com; arc=none smtp.client-ip=45.145.164.37 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=arnaud-lcm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arnaud-lcm.com Received: from 7cf34ddaca59.ant.amazon.com (unknown [IPv6:2a01:e0a:3e8:c0d0:24ce:2523:e0d0:1c47]) by plesk.hostmyservers.fr (Postfix) with ESMTPSA id AFAC74207B; Fri, 5 Sep 2025 13:48:37 +0000 (UTC) Authentication-Results: Plesk; spf=pass (sender IP is 2a01:e0a:3e8:c0d0:24ce:2523:e0d0:1c47) smtp.mailfrom=contact@arnaud-lcm.com smtp.helo=7cf34ddaca59.ant.amazon.com Received-SPF: pass (Plesk: connection is authenticated) From: Arnaud lecomte To: alexei.starovoitov@gmail.com, yonghong.song@linux.dev, song@kernel.org Cc: andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, haoluo@google.com, john.fastabend@gmail.com, jolsa@kernel.org, kpsingh@kernel.org, linux-kernel@vger.kernel.org, martin.lau@linux.dev, sdf@fomichev.me, syzbot+c9b724fbb41cf2538b7b@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, Arnaud Lecomte Subject: [PATCH bpf-next v8 3/3] bpf: fix stackmap overflow check in __bpf_get_stackid() Date: Fri, 5 Sep 2025 15:48:33 +0200 Message-Id: <20250905134833.26791-1-contact@arnaud-lcm.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250905134625.26531-1-contact@arnaud-lcm.com> References: <20250905134625.26531-1-contact@arnaud-lcm.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-PPP-Message-ID: <175708011830.28313.17001961462282681133@Plesk> X-PPP-Vhost: arnaud-lcm.com From: Arnaud Lecomte Syzkaller reported a KASAN slab-out-of-bounds write in __bpf_get_stackid() when copying stack trace data. The issue occurs when the perf trace contains more stack entries than the stack map bucket can hold, leading to an out-of-bounds write in the bucket's data array. Reported-by: syzbot+c9b724fbb41cf2538b7b@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c9b724fbb41cf2538b7b Fixes: ee2a098851bf ("bpf: Adjust BPF stack helper functions to accommodate skip > 0") Signed-off-by: Arnaud Lecomte Acked-by: Yonghong Song --- Changes in v2: - Fixed max_depth names across get stack id Changes in v4: - Removed unnecessary empty line in __bpf_get_stackid Changes in v6: - Added back trace_len computation in __bpf_get_stackid Changes in v7: - Removed usefull trace->nr assignation in bpf_get_stackid_pe - Added restoration of trace->nr for both kernel and user traces in bpf_get_stackid_pe Link to v7: https://lore.kernel.org/all/20250903234325.30212-1-contact@arnaud-lcm.com/ --- kernel/bpf/stackmap.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 9f3ae426ddc3..9b57b8307565 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -369,6 +369,7 @@ BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx, { struct perf_event *event = ctx->event; struct perf_callchain_entry *trace; + u32 elem_size, max_depth; bool kernel, user; __u64 nr_kernel; int ret; @@ -390,15 +391,16 @@ BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx, return -EFAULT; nr_kernel = count_kernel_ip(trace); + elem_size = stack_map_data_size(map); + __u64 nr = trace->nr; /* save original */ if (kernel) { - __u64 nr = trace->nr; - trace->nr = nr_kernel; + max_depth = + stack_map_calculate_max_depth(map->value_size, elem_size, flags); + trace->nr = min_t(u32, nr_kernel, max_depth); ret = __bpf_get_stackid(map, trace, flags); - /* restore nr */ - trace->nr = nr; } else { /* user */ u64 skip = flags & BPF_F_SKIP_FIELD_MASK; @@ -407,8 +409,15 @@ BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx, return -EFAULT; flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip; + max_depth = + stack_map_calculate_max_depth(map->value_size, elem_size, flags); + trace->nr = min_t(u32, trace->nr, max_depth); ret = __bpf_get_stackid(map, trace, flags); } + + /* restore nr */ + trace->nr = nr; + return ret; } -- 2.47.3