Re: [PATCH bpf] bpf: properly check TCP_CONGESTION optlen
From: Alexei Starovoitov <hidden>
Date: 2019-02-23 20:38:14
Also in:
bpf
On Sat, Feb 23, 2019 at 11:07:09AM -0800, Eric Dumazet wrote:
quoted hunk ↗ jump to hunk
If caller of bpf_setsockopt() is silly passing a negative optlen bad things happen. Fixes: 91b5b21c7c16 ("bpf: Add support for changing congestion control") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Lawrence Brakmo <redacted> --- net/core/filter.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)diff --git a/net/core/filter.c b/net/core/filter.c index f7d0004fc16096eb42ece3a6acf645540ee2326b..6a5d89464168f2f35f43986c1dbc0446c9390a3c 100644 --- a/net/core/filter.c +++ b/net/core/filter.c@@ -4194,8 +4194,9 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock, char name[TCP_CA_NAME_MAX]; bool reinit = bpf_sock->op > BPF_SOCK_OPS_NEEDS_ECN; - strncpy(name, optval, min_t(long, optlen, - TCP_CA_NAME_MAX-1)); + if (optlen < 0) + return -EINVAL; + strncpy(name, optval, min(optlen, TCP_CA_NAME_MAX - 1));
Unnecessary.
The verifier guarantees that optlen > 0 because
static const struct bpf_func_proto bpf_setsockopt_proto = {
.func = bpf_setsockopt,
...
.arg5_type = ARG_CONST_SIZE,
};