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bpf: fix stackmap overflow check in __bpf_get_stackid() #9371

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bpf: fix stackmap overflow check in __bpf_get_stackid() #9371

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8 changes: 7 additions & 1 deletion kernel/bpf/stackmap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -230,7 +230,7 @@ static long __bpf_get_stackid(struct bpf_map *map,
struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
struct stack_map_bucket *bucket, *new_bucket, *old_bucket;
u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
u32 hash, id, trace_nr, trace_len, i;
u32 hash, id, trace_nr, trace_len, i, max_depth;
bool user = flags & BPF_F_USER_STACK;
u64 *ips;
bool hash_matches;
Expand All @@ -241,6 +241,12 @@ static long __bpf_get_stackid(struct bpf_map *map,

trace_nr = trace->nr - skip;
trace_len = trace_nr * sizeof(u64);

/* Clamp the trace to max allowed depth */
max_depth = smap->map.value_size / stack_map_data_size(map);
if (trace_nr > max_depth)
trace_nr = max_depth;

ips = trace->ip + skip;
hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0);
id = hash & (smap->n_buckets - 1);
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