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bpf: Check for NULL return from bpf_get_btf_vmlinux 

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: 9492450fd2 ("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
This commit is contained in:
Kumar Kartikeya Dwivedi 2022-03-20 20:00:03 +05:30 committed by Alexei Starovoitov
parent e1cc1f3998
commit 7ada3787e9
2 changed files with 7 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
kernel/bpf/btf.c
View File

@ -534,6 +534,8 @@ static s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p)
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(const struct module *module)
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 *ctx, u32 local_type_id)
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)

2
net/core/bpf_sk_storage.c
View File

@ -406,6 +406,8 @@ static bool bpf_sk_storage_tracing_allowed(const struct bpf_prog *prog)
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);