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    Subject[PATCH 5.10 295/717] bpf: Fix bpf_put_raw_tracepoint()s use of __module_address()
    Date
    From: Andrii Nakryiko <andrii@kernel.org>

    [ Upstream commit 12cc126df82c96c89706aa207ad27c56f219047c ]

    __module_address() needs to be called with preemption disabled or with
    module_mutex taken. preempt_disable() is enough for read-only uses, which is
    what this fix does. Also, module_put() does internal check for NULL, so drop
    it as well.

    Fixes: a38d1107f937 ("bpf: support raw tracepoints in modules")
    Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
    Signed-off-by: Alexei Starovoitov <ast@kernel.org>
    Acked-by: Martin KaFai Lau <kafai@fb.com>
    Link: https://lore.kernel.org/bpf/20201203204634.1325171-2-andrii@kernel.org
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/trace/bpf_trace.c | 8 +++++---
    1 file changed, 5 insertions(+), 3 deletions(-)

    diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
    index a125ea5e04cd7..0dde84b9d29fe 100644
    --- a/kernel/trace/bpf_trace.c
    +++ b/kernel/trace/bpf_trace.c
    @@ -2041,10 +2041,12 @@ struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name)

    void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
    {
    - struct module *mod = __module_address((unsigned long)btp);
    + struct module *mod;

    - if (mod)
    - module_put(mod);
    + preempt_disable();
    + mod = __module_address((unsigned long)btp);
    + module_put(mod);
    + preempt_enable();
    }

    static __always_inline
    --
    2.27.0


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