bpf: fix bpf_prog_array_copy_to_user warning from perf event prog query

syzkaller tried to perform a prog query in perf_event_query_prog_array()
where struct perf_event_query_bpf had an ids_len of 1,073,741,353 and
thus causing a warning due to failed kcalloc() allocation out of the
bpf_prog_array_copy_to_user() helper. Given we cannot attach more than
64 programs to a perf event, there's no point in allowing huge ids_len.
Therefore, allow a buffer that would fix the maximum number of ids and
also add a __GFP_NOWARN to the temporary ids buffer.

Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp")
Fixes: 0911287ce32b ("bpf: fix bpf_prog_array_copy_to_user() issues")
Reported-by: syzbot+cab5816b0edbabf598b3@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 29ca9208dcfadded0633c35387ddb3cd35be6b8b..d315b393abdd0f7dfa67abd706e0f973c3ef2c5a 100644 (file)
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1590,7 +1590,7 @@ int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs,
         * so always copy 'cnt' prog_ids to the user.
         * In a rare race the user will see zero prog_ids
         */
-       ids = kcalloc(cnt, sizeof(u32), GFP_USER);
+       ids = kcalloc(cnt, sizeof(u32), GFP_USER | __GFP_NOWARN);
        if (!ids)
                return -ENOMEM;
        rcu_read_lock();

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index fc2838ac8b7877b1ac16879dbdb178224eb1f0f3..c0a9e310d71501948d60de5f499aa17cb087eaf6 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -872,6 +872,8 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
                return -EINVAL;
        if (copy_from_user(&query, uquery, sizeof(query)))
                return -EFAULT;
+       if (query.ids_len > BPF_TRACE_MAX_PROGS)
+               return -E2BIG;
 
        mutex_lock(&bpf_event_mutex);
        ret = bpf_prog_array_copy_info(event->tp_event->prog_array,