[PATCH 5.10 08/43] bpf: Dont leak memory in bpf getsockopt when optlen == 0

Greg Kroah-Hartman
2021-01-22T14:58:59Z

From: Stanislav Fomichev <sdf@google.com>

commit 4be34f3d0731b38a1b24566b37fbb39500aaf3a2 upstream.

optlen == 0 indicates that the kernel should ignore BPF buffer
and use the original one from the user. We, however, forget
to free the temporary buffer that we've allocated for BPF.

Fixes: d8fe449a9c51 ("bpf: Don't return EINVAL from {get,set}sockopt when optlen > PAGE_SIZE")
Reported-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210112162829.775079-1-sdf@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
kernel/bpf/cgroup.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1391,12 +1391,13 @@ int __cgroup_bpf_run_filter_setsockopt(s
if (ctx.optlen != 0) {
*optlen = ctx.optlen;
*kernel_optval = ctx.optval;
+ /* export and don't free sockopt buf */
+ return 0;
}
}

out:
- if (ret)
- sockopt_free_buf(&ctx);
+ sockopt_free_buf(&ctx);
return ret;
}