From: Peilin Ye <yepeilin...@gmail.com> [ Upstream commit 5b801dfb7feb2738975d80223efc2fc193e55573 ]
Prevent __btf_resolve_helper_id() from dereferencing `btf_vmlinux` as NULL. This patch fixes the following syzbot bug: https://syzkaller.appspot.com/bug?id=f823224ada908fa5c207902a5a62065e53ca0fcc Reported-by: syzbot+ee09bda7017345f1f...@syzkaller.appspotmail.com Signed-off-by: Peilin Ye <yepeilin...@gmail.com> Signed-off-by: Daniel Borkmann <dan...@iogearbox.net> Link: https://lore.kernel.org/bpf/20200714180904.277512-1-yepeilin...@gmail.com Signed-off-by: Sasha Levin <sas...@kernel.org> --- kernel/bpf/btf.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index d1f5d428c9fe2..6cafc596631c3 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -4011,6 +4011,11 @@ static int __btf_resolve_helper_id(struct bpf_verifier_log *log, void *fn, const char *tname, *sym; u32 btf_id, i; + if (!btf_vmlinux) { + bpf_log(log, "btf_vmlinux doesn't exist\n"); + return -EINVAL; + } + if (IS_ERR(btf_vmlinux)) { bpf_log(log, "btf_vmlinux is malformed\n"); return -EINVAL; -- 2.25.1