From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Date: Sun, 20 Mar 2022 20:00:03 +0530
Subject: bpf: Check for NULL return from bpf_get_btf_vmlinux
Patch-mainline: v5.18-rc1
Git-commit: 7ada3787e91c89b0aa7abf47682e8e587b855c13
References: jsc#PED-1377
When CONFIG_DEBUG_INFO_BTF is disabled, bpf_get_btf_vmlinux can return a
NULL pointer. Check for it in btf_get_module_btf to prevent a NULL pointer
dereference.
While kernel test robot only complained about this specific case, let's
also check for NULL in other call sites of bpf_get_btf_vmlinux.
Fixes: 9492450fd287 ("bpf: Always raise reference in btf_get_module_btf")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220320143003.589540-1-memxor@gmail.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
kernel/bpf/btf.c | 6 +++++-
net/core/bpf_sk_storage.c | 2 ++
2 files changed, 7 insertions(+), 1 deletion(-)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -534,6 +534,8 @@ static s32 bpf_find_btf_id(const char *n
btf = bpf_get_btf_vmlinux();
if (IS_ERR(btf))
return PTR_ERR(btf);
+ if (!btf)
+ return -EINVAL;
ret = btf_find_by_name_kind(btf, name, kind);
/* ret is never zero, since btf_find_by_name_kind returns
@@ -6584,7 +6586,7 @@ static struct btf *btf_get_module_btf(co
if (!module) {
btf = bpf_get_btf_vmlinux();
- if (!IS_ERR(btf))
+ if (!IS_ERR_OR_NULL(btf))
btf_get(btf);
return btf;
}
@@ -7180,6 +7182,8 @@ bpf_core_find_cands(struct bpf_core_ctx
main_btf = bpf_get_btf_vmlinux();
if (IS_ERR(main_btf))
return ERR_CAST(main_btf);
+ if (!main_btf)
+ return ERR_PTR(-EINVAL);
local_type = btf_type_by_id(local_btf, local_type_id);
if (!local_type)
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -406,6 +406,8 @@ static bool bpf_sk_storage_tracing_allow
case BPF_TRACE_FENTRY:
case BPF_TRACE_FEXIT:
btf_vmlinux = bpf_get_btf_vmlinux();
+ if (IS_ERR_OR_NULL(btf_vmlinux))
+ return false;
btf_id = prog->aux->attach_btf_id;
t = btf_type_by_id(btf_vmlinux, btf_id);
tname = btf_name_by_offset(btf_vmlinux, t->name_off);