From 7ada3787e91c89b0aa7abf47682e8e587b855c13 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Sun, 20 Mar 2022 20:00:03 +0530 Subject: [PATCH] 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: 9492450fd287 ("bpf: Always raise reference in btf_get_module_btf") Reported-by: kernel test robot Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20220320143003.589540-1-memxor@gmail.com --- kernel/bpf/btf.c | 6 +++++- net/core/bpf_sk_storage.c | 2 ++ 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 6d9e711cb5d4..ce212bf39b2b 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -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) diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c index 7aff1206a851..e3ac36380520 100644 --- a/net/core/bpf_sk_storage.c +++ b/net/core/bpf_sk_storage.c @@ -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);