From: Peilin Ye yepeilin.cs@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=f823224ada908fa5c207902a5a62065e53ca0fc...
Reported-by: syzbot+ee09bda7017345f1fbe6@syzkaller.appspotmail.com Signed-off-by: Peilin Ye yepeilin.cs@gmail.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Link: https://lore.kernel.org/bpf/20200714180904.277512-1-yepeilin.cs@gmail.com Signed-off-by: Sasha Levin sashal@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;