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Revision da353fac65fede6b8b4cfe207f0d9408e3121105 authored by Daniel Jordan on 27 October 2021, 21:59:20 UTC, committed by David S. Miller on 28 October 2021, 13:41:20 UTC 
net/tls: Fix flipped sign in tls_err_abort() calls
 
sk->sk_err appears to expect a positive value, a convention that ktls
doesn't always follow and that leads to memory corruption in other code.
For instance,

    [kworker]
    tls_encrypt_done(..., err=<negative error from crypto request>)
      tls_err_abort(.., err)
        sk->sk_err = err;

    [task]
    splice_from_pipe_feed
      ...
        tls_sw_do_sendpage
          if (sk->sk_err) {
            ret = -sk->sk_err;  // ret is positive

    splice_from_pipe_feed (continued)
      ret = actor(...)  // ret is still positive and interpreted as bytes
                        // written, resulting in underflow of buf->len and
                        // sd->len, leading to huge buf->offset and bogus
                        // addresses computed in later calls to actor()

Fix all tls_err_abort() callers to pass a negative error code
consistently and centralize the error-prone sign flip there, throwing in
a warning to catch future misuse and uninlining the function so it
really does only warn once.

Cc: stable@vger.kernel.org
Fixes: c46234ebb4d1e ("tls: RX path for ktls")
Reported-by: syzbot+b187b77c8474f9648fae@syzkaller.appspotmail.com
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent a32f07d
Raw File
tracex6_kern.c 
#include <linux/ptrace.h>
#include <linux/version.h>
#include <uapi/linux/bpf.h>
#include <bpf/bpf_helpers.h>

struct {
	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
	__uint(key_size, sizeof(int));
	__uint(value_size, sizeof(u32));
	__uint(max_entries, 64);
} counters SEC(".maps");

struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__type(key, int);
	__type(value, u64);
	__uint(max_entries, 64);
} values SEC(".maps");

struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__type(key, int);
	__type(value, struct bpf_perf_event_value);
	__uint(max_entries, 64);
} values2 SEC(".maps");

SEC("kprobe/htab_map_get_next_key")
int bpf_prog1(struct pt_regs *ctx)
{
	u32 key = bpf_get_smp_processor_id();
	u64 count, *val;
	s64 error;

	count = bpf_perf_event_read(&counters, key);
	error = (s64)count;
	if (error <= -2 && error >= -22)
		return 0;

	val = bpf_map_lookup_elem(&values, &key);
	if (val)
		*val = count;
	else
		bpf_map_update_elem(&values, &key, &count, BPF_NOEXIST);

	return 0;
}

SEC("kprobe/htab_map_lookup_elem")
int bpf_prog2(struct pt_regs *ctx)
{
	u32 key = bpf_get_smp_processor_id();
	struct bpf_perf_event_value *val, buf;
	int error;

	error = bpf_perf_event_read_value(&counters, key, &buf, sizeof(buf));
	if (error)
		return 0;

	val = bpf_map_lookup_elem(&values2, &key);
	if (val)
		*val = buf;
	else
		bpf_map_update_elem(&values2, &key, &buf, BPF_NOEXIST);

	return 0;
}

char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;
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