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 0668030ACE3; Sat, 25 Oct 2025 19:29:56 +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=1761420599; cv=none; b=TLNHGK7vMbRn/ek7WX6feNuorOYGK8vcCLvpFfziq5BbqwqIZ8gPva9BtHuljOKDKMZC+eX1rV7c+IWR/VQTHoUWcCZiiOFq+NAJjv06Ck0FlvozofI/Tw+b9uK49AYluS8NZZd0O0jqoSpTvgF9tPeabcbj/808GwBA4V/7q04= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761420599; c=relaxed/simple; bh=BKwSS5n1j+TmCA2j8wQg/7+SCSaYJZVFdLwqBi+78Kc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OSqL47Dkx3DAo4qk/cDTyjcSocDvco8itKRczVv4zqHAm0LgerFP22+4IsyO6FadVcktisHrTdQ5jpdVfr2zTWSbSydWFSoHkymVclmXpXV+QHgUma0gRgjkrRsDcacYex8YO3MURYWzlqE5EbXTOslAgCHO2q6ai3r1kijebEc= 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 dev-dsk-arnaudlc-1a-b66eeb5f.eu-west-1.amazon.com (54-240-197-230.amazon.com [54.240.197.230]) by plesk.hostmyservers.fr (Postfix) with ESMTPSA id 1798640B8D; Sat, 25 Oct 2025 19:29:54 +0000 (UTC) Authentication-Results: Plesk; spf=pass (sender IP is 54.240.197.230) smtp.mailfrom=contact@arnaud-lcm.com smtp.helo=dev-dsk-arnaudlc-1a-b66eeb5f.eu-west-1.amazon.com Received-SPF: pass (Plesk: connection is authenticated) From: Arnaud Lecomte To: contact@arnaud-lcm.com, alexei.starovoitov@gmail.com, andrii.nakryiko@gmail.com, andrii@kernel.org Cc: 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, song@kernel.org, syzbot+c9b724fbb41cf2538b7b@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, yonghong.song@linux.dev Subject: [PATCH V10 RESEND 2/2] bpf: fix stackmap overflow check in __bpf_get_stackid() Date: Sat, 25 Oct 2025 19:29:41 +0000 Message-ID: <20251025192941.1500-1-contact@arnaud-lcm.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251025192858.31424-1-contact@arnaud-lcm.com> References: <20251025192858.31424-1-contact@arnaud-lcm.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-PPP-Message-ID: <176142059485.24744.14432141279233149393@Plesk> X-PPP-Vhost: arnaud-lcm.com 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") Acked-by: Yonghong Song Acked-by: Song Liu Signed-off-by: Arnaud Lecomte --- 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 Changes in v9: - Fixed variable declarations in bpf_get_stackid_pe - Added the missing truncate of trace_nr in __bpf_getstackid Changes in v10: - Remove not required trace->nr = nr_kernel; in bpf_get_stackid_pe Link to v9: https://lore.kernel.org/all/20250912233558.75076-1-contact@arnaud-lcm.com/ --- --- kernel/bpf/stackmap.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 5e9ad050333c..2365541c81dd 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -251,8 +251,8 @@ static long __bpf_get_stackid(struct bpf_map *map, { struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); struct stack_map_bucket *bucket, *new_bucket, *old_bucket; + u32 hash, id, trace_nr, trace_len, i, max_depth; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; - u32 hash, id, trace_nr, trace_len, i; bool user = flags & BPF_F_USER_STACK; u64 *ips; bool hash_matches; @@ -261,7 +261,8 @@ static long __bpf_get_stackid(struct bpf_map *map, /* skipping more than usable stack trace */ return -EFAULT; - trace_nr = trace->nr - skip; + max_depth = stack_map_calculate_max_depth(map->value_size, stack_map_data_size(map), flags); + trace_nr = min_t(u32, trace->nr - skip, max_depth - skip); trace_len = trace_nr * sizeof(u64); ips = trace->ip + skip; hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0); @@ -390,15 +391,11 @@ BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx, return -EFAULT; nr_kernel = count_kernel_ip(trace); + __u64 nr = trace->nr; /* save original */ if (kernel) { - __u64 nr = trace->nr; - trace->nr = nr_kernel; ret = __bpf_get_stackid(map, trace, flags); - - /* restore nr */ - trace->nr = nr; } else { /* user */ u64 skip = flags & BPF_F_SKIP_FIELD_MASK; @@ -409,6 +406,10 @@ BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx, flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip; ret = __bpf_get_stackid(map, trace, flags); } + + /* restore nr */ + trace->nr = nr; + return ret; } -- 2.47.3