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bpf: fix bpf_perf_event_read() helper

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Fix safety checks for bpf_perf_event_read():
- only non-inherited events can be added to perf_event_array map
  (do this check statically at map insertion time)
- dynamically check that event is local and !pmu->count
Otherwise buggy bpf program can cause kernel splat.

Also fix error path after perf_event_attrs()
and remove redundant 'extern'.

Fixes: 35578d7984 ("bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2015-10-22 17:10:14 -07:00 • committed by David S. Miller
parent 8b7c94e347
commit 62544ce8e0
3 changed files with 22 additions and 11 deletions
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25
kernel/bpf/arraymap.c
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@ -292,16 +292,23 @@ static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd)
attr = perf_event_attrs(event);
if (IS_ERR(attr))
return (void *)attr;
goto err;
if (attr->type != PERF_TYPE_RAW &&
!(attr->type == PERF_TYPE_SOFTWARE &&
attr->config == PERF_COUNT_SW_BPF_OUTPUT) &&
attr->type != PERF_TYPE_HARDWARE) {
perf_event_release_kernel(event);
return ERR_PTR(-EINVAL);
}
return event;
if (attr->inherit)
goto err;
if (attr->type == PERF_TYPE_RAW)
return event;
if (attr->type == PERF_TYPE_HARDWARE)
return event;
if (attr->type == PERF_TYPE_SOFTWARE &&
attr->config == PERF_COUNT_SW_BPF_OUTPUT)
return event;
err:
perf_event_release_kernel(event);
return ERR_PTR(-EINVAL);
}
static void perf_event_fd_array_put_ptr(void *ptr)