From: Yuntao Wang ytcoode@gmail.com
commit a2aa95b71c9bbec793b5c5fa50f0a80d882b3e8d upstream.
The cnt value in the 'cnt >= BPF_MAX_TRAMP_PROGS' check does not include BPF_TRAMP_MODIFY_RETURN bpf programs, so the number of the attached BPF_TRAMP_MODIFY_RETURN bpf programs in a trampoline can exceed BPF_MAX_TRAMP_PROGS.
When this happens, the assignment '*progs++ = aux->prog' in bpf_trampoline_get_progs() will cause progs array overflow as the progs field in the bpf_tramp_progs struct can only hold at most BPF_MAX_TRAMP_PROGS bpf programs.
Fixes: 88fd9e5352fe ("bpf: Refactor trampoline update code") Signed-off-by: Yuntao Wang ytcoode@gmail.com Link: https://lore.kernel.org/r/20220430130803.210624-1-ytcoode@gmail.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/bpf/trampoline.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)
--- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -423,7 +423,7 @@ int bpf_trampoline_link_prog(struct bpf_ { enum bpf_tramp_prog_type kind; int err = 0; - int cnt; + int cnt = 0, i;
kind = bpf_attach_type_to_tramp(prog); mutex_lock(&tr->mutex); @@ -434,7 +434,10 @@ int bpf_trampoline_link_prog(struct bpf_ err = -EBUSY; goto out; } - cnt = tr->progs_cnt[BPF_TRAMP_FENTRY] + tr->progs_cnt[BPF_TRAMP_FEXIT]; + + for (i = 0; i < BPF_TRAMP_MAX; i++) + cnt += tr->progs_cnt[i]; + if (kind == BPF_TRAMP_REPLACE) { /* Cannot attach extension if fentry/fexit are in use. */ if (cnt) { @@ -512,16 +515,19 @@ out:
void bpf_trampoline_put(struct bpf_trampoline *tr) { + int i; + if (!tr) return; mutex_lock(&trampoline_mutex); if (!refcount_dec_and_test(&tr->refcnt)) goto out; WARN_ON_ONCE(mutex_is_locked(&tr->mutex)); - if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[BPF_TRAMP_FENTRY]))) - goto out; - if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[BPF_TRAMP_FEXIT]))) - goto out; + + for (i = 0; i < BPF_TRAMP_MAX; i++) + if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[i]))) + goto out; + /* This code will be executed even when the last bpf_tramp_image * is alive. All progs are detached from the trampoline and the * trampoline image is patched with jmp into epilogue to skip