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Commit 7d1982b4 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Alexei Starovoitov
Browse files

bpf: fix panic in prog load calls cleanup 



While testing I found that when hitting error path in bpf_prog_load()
where we jump to free_used_maps and prog contained BPF to BPF calls
that were JITed earlier, then we never clean up the bpf_prog_kallsyms_add()
done under jit_subprogs(). Add proper API to make BPF kallsyms deletion
more clear and fix that.

Fixes: 1c2a088a ("bpf: x64: add JIT support for multi-function programs")
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 26bf8a89

include/linux/filter.h

+3 −0
Original line number Diff line number Diff line
@@ -961,6 +961,9 @@ static inline void bpf_prog_kallsyms_del(struct bpf_prog *fp) 
}

#endif /* CONFIG_BPF_JIT */



void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp);

void bpf_prog_kallsyms_del_all(struct bpf_prog *fp);



#define BPF_ANC		BIT(15)



static inline bool bpf_needs_clear_a(const struct sock_filter *first)

kernel/bpf/core.c

+14 −0
Original line number Diff line number Diff line
@@ -350,6 +350,20 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, 
	return prog_adj;

}



void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp)

{

	int i;



	for (i = 0; i < fp->aux->func_cnt; i++)

		bpf_prog_kallsyms_del(fp->aux->func[i]);

}



void bpf_prog_kallsyms_del_all(struct bpf_prog *fp)

{

	bpf_prog_kallsyms_del_subprogs(fp);

	bpf_prog_kallsyms_del(fp);

}



#ifdef CONFIG_BPF_JIT

/* All BPF JIT sysctl knobs here. */

int bpf_jit_enable   __read_mostly = IS_BUILTIN(CONFIG_BPF_JIT_ALWAYS_ON);

kernel/bpf/syscall.c

+2 −6
Original line number Diff line number Diff line
@@ -1034,14 +1034,9 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu) 
static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)

{

	if (atomic_dec_and_test(&prog->aux->refcnt)) {

		int i;



		/* bpf_prog_free_id() must be called first */

		bpf_prog_free_id(prog, do_idr_lock);



		for (i = 0; i < prog->aux->func_cnt; i++)

			bpf_prog_kallsyms_del(prog->aux->func[i]);

		bpf_prog_kallsyms_del(prog);

		bpf_prog_kallsyms_del_all(prog);



		call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);

	}
@@ -1384,6 +1379,7 @@ static int bpf_prog_load(union bpf_attr *attr) 
	return err;



free_used_maps:

	bpf_prog_kallsyms_del_subprogs(prog);

	free_used_maps(prog->aux);

free_prog:

	bpf_prog_uncharge_memlock(prog);