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bpf: Disable migration when cloning sock storage 

bpf_sk_storage_clone() will call bpf_selem_free() to free the clone
element when the allocation of new sock storage fails. bpf_selem_free()
will call check_and_free_fields() to free the special fields in the
element. Since the allocated element is not visible to bpf syscall or
bpf program when bpf_local_storage_alloc() fails, these special fields
in the element must be all zero when invoking bpf_selem_free().

To be uniform with other callers of bpf_selem_free(), disabling
migration when cloning sock storage. Adding migrate_{disable|enable}
pair also benefits the potential switching from kzalloc to bpf memory
allocator for sock storage.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-9-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Hou Tao 2025-01-08 09:07:20 +08:00 committed by Alexei Starovoitov
parent 7d1032d1e3
commit dfccfc47bd
1 changed files with 2 additions and 0 deletions
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2
net/core/bpf_sk_storage.c
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@ -161,6 +161,7 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk)
RCU_INIT_POINTER(newsk->sk_bpf_storage, NULL);
migrate_disable();
rcu_read_lock();
sk_storage = rcu_dereference(sk->sk_bpf_storage);
@ -213,6 +214,7 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk)
out:
rcu_read_unlock();
migrate_enable();
/* In case of an error, don't free anything explicitly here, the
* caller is responsible to call bpf_sk_storage_free.