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 4479C2E8E0F; Wed, 3 Sep 2025 13:53:52 +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=1756907634; cv=none; b=q3nmsWO7hBZmZLK+ahEOcQwWk/tSz2vPU1NbFqcmpEsNZqC0hxkctIHRM1BJz/K0EcOBean2mCdIMpEh1t2KItjIk3LBWXPYqN5kyQS8ulziJgDJvD/QFuuA7sQGc5Vyp+C61uWp1lxLnaa+/y3ark/r1Rt27jHWX6fsezz6QVo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756907634; c=relaxed/simple; bh=j+kPGOFhynhpG0gp3DoKa1yVPSbzCmQcI8JJg2ZKe/0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=TjvDk+ecjW1LRDEPSyY4+byXTHVgVsAG9P2wT9BRvsjA24xrNZMs2FPz83j26uLEsjpWASVndR9z0IdhMyfyvdrYwJCAj5wKQeao9sZeY9UZhKrem/7WIMcrB4iBfFalP7Yk9MNnSvL6nRRkfwAw4iKQkCPpcNxhq1AKeYJ/y+I= 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:f888:35a:53a4:66b4]) by plesk.hostmyservers.fr (Postfix) with ESMTPSA id CDF154213E; Wed, 3 Sep 2025 13:53:49 +0000 (UTC) Authentication-Results: Plesk; spf=pass (sender IP is 2a01:e0a:3e8:c0d0:f888:35a:53a4:66b4) 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 v6 2/2] bpf: fix stackmap overflow check in __bpf_get_stackid() Date: Wed, 3 Sep 2025 15:53:48 +0200 Message-Id: <20250903135348.97884-1-contact@arnaud-lcm.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250903135222.97604-1-contact@arnaud-lcm.com> References: <20250903135222.97604-1-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: <175690763045.28809.1530218238142963216@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. Changes in v2: - Fixed max_depth names across get stack id Changes in v4: - Removed unnecessary empty line in __bpf_get_stackid Changs in v6: - Added back trace_len computation in __bpf_get_stackid Link to v5: https://lore.kernel.org/all/20250826212229.143230-1-contact@arnaud-lcm.com/ 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 --- kernel/bpf/stackmap.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 1ebc525b7c2f..8b2dcb8a6dc3 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -251,8 +251,9 @@ 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; + u32 elem_size = stack_map_data_size(map); bool user = flags & BPF_F_USER_STACK; u64 *ips; bool hash_matches; @@ -261,8 +262,12 @@ static long __bpf_get_stackid(struct bpf_map *map, /* skipping more than usable stack trace */ return -EFAULT; + max_depth = + stack_map_calculate_max_depth(map->value_size, elem_size, flags); trace_nr = trace->nr - skip; + trace_nr = min_t(u32, trace_nr, max_depth - skip); trace_len = trace_nr * sizeof(u64); + ips = trace->ip + skip; hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0); id = hash & (smap->n_buckets - 1); -- 2.47.3