diff options
| author | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2022-02-17 01:49:43 +0530 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-02-16 12:46:51 -0800 |
| commit | 45ce4b4f9009102cd9f581196d480a59208690c1 (patch) | |
| tree | 806a5cc566416b243fb0fabc7a7adbf7ab97efea /kernel | |
| parent | 61d06f01f9710b327a53492e5add9f972eb909b3 (diff) | |
bpf: Fix crash due to out of bounds access into reg2btf_ids.
When commit e6ac2450d6de ("bpf: Support bpf program calling kernel function") added
kfunc support, it defined reg2btf_ids as a cheap way to translate the verifier
reg type to the appropriate btf_vmlinux BTF ID, however
commit c25b2ae13603 ("bpf: Replace PTR_TO_XXX_OR_NULL with PTR_TO_XXX | PTR_MAYBE_NULL")
moved the __BPF_REG_TYPE_MAX from the last member of bpf_reg_type enum to after
the base register types, and defined other variants using type flag
composition. However, now, the direct usage of reg->type to index into
reg2btf_ids may no longer fall into __BPF_REG_TYPE_MAX range, and hence lead to
out of bounds access and kernel crash on dereference of bad pointer.
Fixes: c25b2ae13603 ("bpf: Replace PTR_TO_XXX_OR_NULL with PTR_TO_XXX | PTR_MAYBE_NULL")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220216201943.624869-1-memxor@gmail.com
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/btf.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index e16dafeb2450..3e23b3fa79ff 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -5688,7 +5688,8 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, } if (check_ptr_off_reg(env, reg, regno)) return -EINVAL; - } else if (is_kfunc && (reg->type == PTR_TO_BTF_ID || reg2btf_ids[reg->type])) { + } else if (is_kfunc && (reg->type == PTR_TO_BTF_ID || + (reg2btf_ids[base_type(reg->type)] && !type_flag(reg->type)))) { const struct btf_type *reg_ref_t; const struct btf *reg_btf; const char *reg_ref_tname; @@ -5706,7 +5707,7 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, reg_ref_id = reg->btf_id; } else { reg_btf = btf_vmlinux; - reg_ref_id = *reg2btf_ids[reg->type]; + reg_ref_id = *reg2btf_ids[base_type(reg->type)]; } reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id, |