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bpf: Fix cgroup local storage prog tracking

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Recently noticed that we're tracking programs related to local storage maps
through their prog pointer. This is a wrong assumption since the prog pointer
can still change throughout the verification process, for example, whenever
bpf_patch_insn_single() is called.

Therefore, the prog pointer that was assigned via bpf_cgroup_storage_assign()
is not guaranteed to be the same as we pass in bpf_cgroup_storage_release()
and the map would therefore remain in busy state forever. Fix this by using
the prog's aux pointer which is stable throughout verification and beyond.

Fixes: de9cbbaadb ("bpf: introduce cgroup storage maps")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/1471c69eca3022218666f909bc927a92388fd09e.1576580332.git.daniel@iogearbox.net
This commit is contained in:
Daniel Borkmann
2019-12-17 13:28:16 +01:00
committed by Alexei Starovoitov
parent a2ea07465c
commit e47304232b
4 changed files with 18 additions and 19 deletions
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3
kernel/bpf/core.c
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@@ -2043,8 +2043,7 @@ static void bpf_free_cgroup_storage(struct bpf_prog_aux *aux)
for_each_cgroup_storage_type(stype) {
if (!aux->cgroup_storage[stype])
continue;
bpf_cgroup_storage_release(aux->prog,
aux->cgroup_storage[stype]);
bpf_cgroup_storage_release(aux, aux->cgroup_storage[stype]);
}
}