bpf: Free special fields when update hash and local storage maps #10100
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As [lru_,]percpu_hash maps support BPF_KPTR_{REF,PERCPU}, missing
calls to 'bpf_obj_free_fields()' in 'pcpu_copy_value()' could cause the
memory referenced by BPF_KPTR_{REF,PERCPU} fields to be held until the
map gets freed.
Fix this by calling 'bpf_obj_free_fields()' after
'copy_map_value[,_long]()' in 'pcpu_copy_value()'.
Fixes: 65334e6 ("bpf: Support kptrs in percpu hashmap and percpu LRU hashmap")
Signed-off-by: Leon Hwang <[email protected]>
When updating hash maps with BPF_F_LOCK, the special fields were not
freed after being replaced. This could cause memory referenced by
BPF_KPTR_{REF,PERCPU} fields to be held until the map gets freed.
Fix this by calling 'check_and_free_fields()' after
'copy_map_value_locked()' to properly release the old fields.
Fixes: 14a324f ("bpf: Wire up freeing of referenced kptr")
Signed-off-by: Leon Hwang <[email protected]>
When updating local storage maps with BPF_F_LOCK on the fast path, the
special fields were not freed after being replaced. This could cause
memory referenced by BPF_KPTR_{REF,PERCPU} fields to be held until the
map gets freed.
Similarly, on the other path, the old sdata's special fields were never
freed regardless of whether BPF_F_LOCK was used, causing the same issue.
Fix this by calling 'bpf_obj_free_fields()' after
'copy_map_value_locked()' to properly release the old fields.
Fixes: 9db44fd ("bpf: Support kptrs in local storage maps")
Signed-off-by: Leon Hwang <[email protected]>
…date hash and local storage maps Add tests to verify that updating hash and local storage maps decrements refcount when BPF_KPTR_REF objects are involved. The tests perform the following steps: 1. Call update_elem() to insert an initial value. 2. Use bpf_refcount_acquire() to increment the refcount. 3. Store the node pointer in the map value. 4. Add the node to a linked list. 5. Probe-read the refcount and verify it is *2*. 6. Call update_elem() again to trigger refcount decrement. 7. Probe-read the refcount and verify it is *1*. Signed-off-by: Leon Hwang <[email protected]>
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