Messages in this thread Patch in this message | | | Date | Wed, 13 Oct 2021 18:37:03 -0700 | Subject | [PATCH v2] tracing/cfi: Fix cmp_entries_* functions signature mismatch | From | Kalesh Singh <> |
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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.
Signed-off-by: Kalesh Singh <kaleshsingh@google.com> --- Changes in v2: - Code style clean up, per Steve - Commit message typo fix, per Steve
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 d6bddb157ef2..4f91a81dd838 100644 --- a/kernel/trace/tracing_map.c +++ b/kernel/trace/tracing_map.c @@ -834,20 +834,26 @@ 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 **pa = A; + const struct tracing_map_sort_entry **pb = B; + const struct tracing_map_sort_entry *a = *pa; + const struct tracing_map_sort_entry *b = *pb; int ret = 0; - if (memcmp((*a)->key, (*b)->key, (*a)->elt->map->key_size)) + 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_sort_entry **pa = A; + const struct tracing_map_sort_entry **pb = B; + const struct tracing_map_sort_entry *a = *pa; + const struct tracing_map_sort_entry *b = *pb; const struct tracing_map_elt *elt_a, *elt_b; struct tracing_map_sort_key *sort_key; struct tracing_map_field *field; @@ -855,8 +861,8 @@ static int cmp_entries_sum(const struct tracing_map_sort_entry **a, void *val_a, *val_b; int ret = 0; - elt_a = (*a)->elt; - elt_b = (*b)->elt; + elt_a = a->elt; + elt_b = b->elt; sort_key = &elt_a->map->sort_key; @@ -873,9 +879,12 @@ 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_sort_entry **pa = A; + const struct tracing_map_sort_entry **pb = B; + const struct tracing_map_sort_entry *a = *pa; + const struct tracing_map_sort_entry *b = *pb; const struct tracing_map_elt *elt_a, *elt_b; struct tracing_map_sort_key *sort_key; struct tracing_map_field *field; @@ -883,8 +892,8 @@ static int cmp_entries_key(const struct tracing_map_sort_entry **a, void *val_a, *val_b; int ret = 0; - elt_a = (*a)->elt; - elt_b = (*b)->elt; + elt_a = a->elt; + elt_b = b->elt; sort_key = &elt_a->map->sort_key; @@ -989,10 +998,8 @@ 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)) @@ -1061,8 +1068,7 @@ 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; base-commit: 348949d9a4440abdab3b1dc99a9bb660e8c7da7c -- 2.33.0.1079.g6e70778dc9-goog
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