Prevent __btf_resolve_helper_id() from dereferencing `btf_vmlinux`
as NULL. This patch fixes the following syzbot bug:
https://syzkaller.appspot.com/bug?id=5edd146856fd513747c1992442732e5a0e9ba355
Reported-by: syzbot+ee09bda7017345f1fbe6@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Peilin Ye <yepeilin.cs@xxxxxxxxx>
---
Thank you for reviewing my patch! I am new to Linux kernel development; would
the log message and errno be appropriate for this case?
Change in v2:
- Split NULL and IS_ERR cases.
kernel/bpf/btf.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 30721f2c2d10..092116a311f4 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -4088,6 +4088,11 @@ 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
