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authorDaniel Borkmann <daniel@iogearbox.net>2019-10-22 23:30:38 +0200
committerAlexei Starovoitov <ast@kernel.org>2019-10-23 06:59:49 +0200
commit3b4d9eb2ee74dd5ea7fa36cffb0ca7f5bc4924da (patch)
tree607611b86e1c20fa53a090e13a279e5bcfcd850d /kernel
parentbpf: Fix use after free in subprog's jited symbol removal (diff)
downloadlinux-3b4d9eb2ee74dd5ea7fa36cffb0ca7f5bc4924da.tar.xz
linux-3b4d9eb2ee74dd5ea7fa36cffb0ca7f5bc4924da.zip
bpf: Fix use after free in bpf_get_prog_name
There is one more problematic case I noticed while recently fixing BPF kallsyms handling in cd7455f1013e ("bpf: Fix use after free in subprog's jited symbol removal") and that is bpf_get_prog_name(). If BTF has been attached to the prog, then we may be able to fetch the function signature type id in kallsyms through prog->aux->func_info[prog->aux->func_idx].type_id. However, while the BTF object itself is torn down via RCU callback, the prog's aux->func_info is immediately freed via kvfree(prog->aux->func_info) once the prog's refcount either hit zero or when subprograms were already exposed via kallsyms and we hit the error path added in 5482e9a93c83 ("bpf: Fix memleak in aux->func_info and aux->btf"). This violates RCU as well since kallsyms could be walked in parallel where we could access aux->func_info. Hence, defer kvfree() to after RCU grace period. Looking at ba64e7d85252 ("bpf: btf: support proper non-jit func info") there is no reason/dependency where we couldn't defer the kvfree(aux->func_info) into the RCU callback. Fixes: 5482e9a93c83 ("bpf: Fix memleak in aux->func_info and aux->btf") Fixes: ba64e7d85252 ("bpf: btf: support proper non-jit func info") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Cc: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/875f2906a7c1a0691f2d567b4d8e4ea2739b1e88.1571779205.git.daniel@iogearbox.net
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/syscall.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index bcfc362de4f2..0937719b87e2 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1326,6 +1326,7 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu)
{
struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu);
+ kvfree(aux->func_info);
free_used_maps(aux);
bpf_prog_uncharge_memlock(aux->prog);
security_bpf_prog_free(aux);
@@ -1336,7 +1337,6 @@ static void __bpf_prog_put_noref(struct bpf_prog *prog, bool deferred)
{
bpf_prog_kallsyms_del_all(prog);
btf_put(prog->aux->btf);
- kvfree(prog->aux->func_info);
bpf_prog_free_linfo(prog);
if (deferred)