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bpf: fix panic in prog load calls cleanup

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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: 1c2a088a66 ("bpf: x64: add JIT support for multi-function programs")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel Borkmann 2018-06-15 02:30:47 +02:00 committed by Alexei Starovoitov
parent 26bf8a89d8
commit 7d1982b4e3
3 changed files with 19 additions and 6 deletions
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3
include/linux/filter.h
View File

@ -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)

14
kernel/bpf/core.c
View File

@ -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);

8
kernel/bpf/syscall.c
View File

@ -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);