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: f371b304f1 ("bpf/tracing: allow user space to query prog array on the same tp")
Fixes: 0911287ce3 ("bpf: fix bpf_prog_array_copy_to_user() issues")
Reported-by: [email protected]
Signed-off-by: Daniel Borkmann <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>
This commit is contained in:
Daniel Borkmann 2018-02-14 15:31:00 +01:00 • committed by Alexei Starovoitov
commit 9c481b908b
2 changed files with 3 additions and 1 deletions

View file

@ -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();