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    Subject[PATCH -tip v3 05/10] kprobes: Search non-suffixed symbol in blacklist
    Date
    Newer gcc can generate some different instances of a function
    with suffixed symbols if the function is optimized and only
    has a part of that. (e.g. .constprop, .part etc.)

    In this case, it is not enough to check the entry of kprobe
    blacklist because it only records non-suffixed symbol address.

    To fix this issue, search non-suffixed symbol in blacklist if
    given address is within a symbol which has a suffix.

    Note that this can cause false positive cases if a kprobe-safe
    function is optimized to suffixed instance and has same name
    symbol which is blacklisted.
    But I would like to chose a fail-safe design for this issue.

    Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
    ---
    kernel/kprobes.c | 21 ++++++++++++++++++++-
    1 file changed, 20 insertions(+), 1 deletion(-)

    diff --git a/kernel/kprobes.c b/kernel/kprobes.c
    index f4ddfdd2d07e..c83e54727131 100644
    --- a/kernel/kprobes.c
    +++ b/kernel/kprobes.c
    @@ -1396,7 +1396,7 @@ bool __weak arch_within_kprobe_blacklist(unsigned long addr)
    addr < (unsigned long)__kprobes_text_end;
    }

    -bool within_kprobe_blacklist(unsigned long addr)
    +static bool __within_kprobe_blacklist(unsigned long addr)
    {
    struct kprobe_blacklist_entry *ent;

    @@ -1410,7 +1410,26 @@ bool within_kprobe_blacklist(unsigned long addr)
    if (addr >= ent->start_addr && addr < ent->end_addr)
    return true;
    }
    + return false;
    +}

    +bool within_kprobe_blacklist(unsigned long addr)
    +{
    + char symname[KSYM_NAME_LEN], *p;
    +
    + if (__within_kprobe_blacklist(addr))
    + return true;
    +
    + /* Check if the address is on a suffixed-symbol */
    + if (!lookup_symbol_name(addr, symname)) {
    + p = strchr(symname, '.');
    + if (!p)
    + return false;
    + *p = '\0';
    + addr = (unsigned long)kprobe_lookup_name(symname, 0);
    + if (addr)
    + return __within_kprobe_blacklist(addr);
    + }
    return false;
    }

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