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    Subject[PATCH AUTOSEL 4.19 030/100] samples: bpf: fix: seg fault with NULL pointer arg
    Date
    From: "Daniel T. Lee" <danieltimlee@gmail.com>

    [ Upstream commit d59dd69d5576d699d7d3f5da0b4738c3a36d0133 ]

    When NULL pointer accidentally passed to write_kprobe_events,
    due to strlen(NULL), segmentation fault happens.
    Changed code returns -1 to deal with this situation.

    Bug issued with Smatch, static analysis.

    Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
    Acked-by: Song Liu <songliubraving@fb.com>
    Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    samples/bpf/bpf_load.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
    index 5061a2ec45646..176c04a454dc9 100644
    --- a/samples/bpf/bpf_load.c
    +++ b/samples/bpf/bpf_load.c
    @@ -59,7 +59,9 @@ static int write_kprobe_events(const char *val)
    {
    int fd, ret, flags;

    - if ((val != NULL) && (val[0] == '\0'))
    + if (val == NULL)
    + return -1;
    + else if (val[0] == '\0')
    flags = O_WRONLY | O_TRUNC;
    else
    flags = O_WRONLY | O_APPEND;
    --
    2.20.1
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