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    Subject[PATCH 4.9 078/207] tracing/cfi: Fix cmp_entries_* functions signature mismatch
    Date
    From: Kalesh Singh <kaleshsingh@google.com>

    [ Upstream commit 7ce1bb83a14019f8c396d57ec704d19478747716 ]

    If CONFIG_CFI_CLANG=y, attempting to read an event histogram will cause
    the kernel to panic due to failed CFI check.

    1. echo 'hist:keys=common_pid' >> events/sched/sched_switch/trigger
    2. cat events/sched/sched_switch/hist
    3. kernel panics on attempting to read hist

    This happens because the sort() function expects a generic
    int (*)(const void *, const void *) pointer for the compare function.
    To prevent this CFI failure, change tracing map cmp_entries_* function
    signatures to match this.

    Also, fix the build error reported by the kernel test robot [1].

    [1] https://lore.kernel.org/r/202110141140.zzi4dRh4-lkp@intel.com/

    Link: https://lkml.kernel.org/r/20211014045217.3265162-1-kaleshsingh@google.com

    Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
    Reported-by: kernel test robot <lkp@intel.com>
    Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/trace/tracing_map.c | 40 ++++++++++++++++++++++----------------
    1 file changed, 23 insertions(+), 17 deletions(-)

    diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c
    index 35b2ba07f3c6f..379db35838b64 100644
    --- a/kernel/trace/tracing_map.c
    +++ b/kernel/trace/tracing_map.c
    @@ -703,29 +703,35 @@ int tracing_map_init(struct tracing_map *map)
    return err;
    }

    -static int cmp_entries_dup(const struct tracing_map_sort_entry **a,
    - const struct tracing_map_sort_entry **b)
    +static int cmp_entries_dup(const void *A, const void *B)
    {
    + const struct tracing_map_sort_entry *a, *b;
    int ret = 0;

    - if (memcmp((*a)->key, (*b)->key, (*a)->elt->map->key_size))
    + a = *(const struct tracing_map_sort_entry **)A;
    + b = *(const struct tracing_map_sort_entry **)B;
    +
    + if (memcmp(a->key, b->key, a->elt->map->key_size))
    ret = 1;

    return ret;
    }

    -static int cmp_entries_sum(const struct tracing_map_sort_entry **a,
    - const struct tracing_map_sort_entry **b)
    +static int cmp_entries_sum(const void *A, const void *B)
    {
    const struct tracing_map_elt *elt_a, *elt_b;
    + const struct tracing_map_sort_entry *a, *b;
    struct tracing_map_sort_key *sort_key;
    struct tracing_map_field *field;
    tracing_map_cmp_fn_t cmp_fn;
    void *val_a, *val_b;
    int ret = 0;

    - elt_a = (*a)->elt;
    - elt_b = (*b)->elt;
    + a = *(const struct tracing_map_sort_entry **)A;
    + b = *(const struct tracing_map_sort_entry **)B;
    +
    + elt_a = a->elt;
    + elt_b = b->elt;

    sort_key = &elt_a->map->sort_key;

    @@ -742,18 +748,21 @@ static int cmp_entries_sum(const struct tracing_map_sort_entry **a,
    return ret;
    }

    -static int cmp_entries_key(const struct tracing_map_sort_entry **a,
    - const struct tracing_map_sort_entry **b)
    +static int cmp_entries_key(const void *A, const void *B)
    {
    const struct tracing_map_elt *elt_a, *elt_b;
    + const struct tracing_map_sort_entry *a, *b;
    struct tracing_map_sort_key *sort_key;
    struct tracing_map_field *field;
    tracing_map_cmp_fn_t cmp_fn;
    void *val_a, *val_b;
    int ret = 0;

    - elt_a = (*a)->elt;
    - elt_b = (*b)->elt;
    + a = *(const struct tracing_map_sort_entry **)A;
    + b = *(const struct tracing_map_sort_entry **)B;
    +
    + elt_a = a->elt;
    + elt_b = b->elt;

    sort_key = &elt_a->map->sort_key;

    @@ -926,10 +935,8 @@ static void sort_secondary(struct tracing_map *map,
    struct tracing_map_sort_key *primary_key,
    struct tracing_map_sort_key *secondary_key)
    {
    - int (*primary_fn)(const struct tracing_map_sort_entry **,
    - const struct tracing_map_sort_entry **);
    - int (*secondary_fn)(const struct tracing_map_sort_entry **,
    - const struct tracing_map_sort_entry **);
    + int (*primary_fn)(const void *, const void *);
    + int (*secondary_fn)(const void *, const void *);
    unsigned i, start = 0, n_sub = 1;

    if (is_key(map, primary_key->field_idx))
    @@ -998,8 +1005,7 @@ int tracing_map_sort_entries(struct tracing_map *map,
    unsigned int n_sort_keys,
    struct tracing_map_sort_entry ***sort_entries)
    {
    - int (*cmp_entries_fn)(const struct tracing_map_sort_entry **,
    - const struct tracing_map_sort_entry **);
    + int (*cmp_entries_fn)(const void *, const void *);
    struct tracing_map_sort_entry *sort_entry, **entries;
    int i, n_entries, ret;

    --
    2.33.0


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