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    Subject[PATCH 5.6 063/126] bpf: Add bpf_probe_read_{user, kernel}_str() to do_refine_retval_range
    Date
    From: Daniel Borkmann <daniel@iogearbox.net>

    commit 47cc0ed574abcbbde0cf143ddb21a0baed1aa2df upstream.

    Given bpf_probe_read{,str}() BPF helpers are now only available under
    CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE, we need to add the drop-in
    replacements of bpf_probe_read_{kernel,user}_str() to do_refine_retval_range()
    as well to avoid hitting the same issue as in 849fa50662fbc ("bpf/verifier:
    refine retval R0 state for bpf_get_stack helper").

    Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
    Signed-off-by: Alexei Starovoitov <ast@kernel.org>
    Acked-by: John Fastabend <john.fastabend@gmail.com>
    Acked-by: Yonghong Song <yhs@fb.com>
    Link: https://lore.kernel.org/bpf/20200515101118.6508-3-daniel@iogearbox.net
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/bpf/verifier.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    --- a/kernel/bpf/verifier.c
    +++ b/kernel/bpf/verifier.c
    @@ -4113,7 +4113,9 @@ static int do_refine_retval_range(struct

    if (ret_type != RET_INTEGER ||
    (func_id != BPF_FUNC_get_stack &&
    - func_id != BPF_FUNC_probe_read_str))
    + func_id != BPF_FUNC_probe_read_str &&
    + func_id != BPF_FUNC_probe_read_kernel_str &&
    + func_id != BPF_FUNC_probe_read_user_str))
    return 0;

    /* Error case where ret is in interval [S32MIN, -1]. */

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