From 7d1982b4e335c1b184406b7566f6041bfe313c35 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 15 Jun 2018 02:30:47 +0200 Subject: [PATCH] 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: 1c2a088a6626 ("bpf: x64: add JIT support for multi-function programs") Signed-off-by: Daniel Borkmann Acked-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov --- include/linux/filter.h | 3 +++ kernel/bpf/core.c | 14 ++++++++++++++ kernel/bpf/syscall.c | 8 ++------ 3 files changed, 19 insertions(+), 6 deletions(-) diff --git a/include/linux/filter.h b/include/linux/filter.h index 45fc0f5000d8..297c56fa9cee 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -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) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 9f1493705f40..1061968adcc1 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -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); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 0fa20624707f..0f62692fe635 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -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);