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From: Sean Young <sean@mess.org>
To: linux-media@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
Subject: [PATCH] media: bpf: do not copy more entries than user space requested
Date: Wed, 23 Jun 2021 22:37:54 +0100	[thread overview]
Message-ID: <20210623213754.632-1-sean@mess.org> (raw)

The syscall bpf(BPF_PROG_QUERY, &attr) should the prog_cnt field to see
how many entries user space provided and return ENOSPC if there are
more programs than that. Before this patch, this is not checked and
ENOSPC is never returned.

Note that one lirc device is limited to 64 bpf programs, and user space
I'm aware of -- ir-keytable -- always gives enough space for 64 entries
already. However, we should not copy program ids than are requested.

Signed-off-by: Sean Young <sean@mess.org>
 drivers/media/rc/bpf-lirc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/rc/bpf-lirc.c b/drivers/media/rc/bpf-lirc.c
index 3fe3edd80876..afae0afe3f81 100644
--- a/drivers/media/rc/bpf-lirc.c
+++ b/drivers/media/rc/bpf-lirc.c
@@ -326,7 +326,8 @@ int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
 	if (attr->query.prog_cnt != 0 && prog_ids && cnt)
-		ret = bpf_prog_array_copy_to_user(progs, prog_ids, cnt);
+		ret = bpf_prog_array_copy_to_user(progs, prog_ids,
+						  attr->query.prog_cnt);

             reply	other threads:[~2021-06-23 21:37 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-23 21:37 Sean Young [this message]
2021-06-24  9:21 ` [PATCH] media: bpf: do not copy more entries than user space requested Sean Young
2021-06-24 13:40 ` patchwork-bot+netdevbpf

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