Re: [Linux-kernel-mentees] [PATCH] bpf: Fix NULL pointer dereference in __btf_resolve_helper_id()
From: Andrii Nakryiko <hidden>
Date: 2020-07-14 00:53:45
Also in:
bpf, lkml, netdev
On Mon, Jul 13, 2020 at 5:43 PM Peilin Ye [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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@syzkaller.appspotmail.com Signed-off-by: Peilin Ye <redacted> --- kernel/bpf/btf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 30721f2c2d10..3e981b183fa4 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c@@ -4088,7 +4088,7 @@ static int __btf_resolve_helper_id(struct bpf_verifier_log *log, void *fn, const char *tname, *sym; u32 btf_id, i; - if (IS_ERR(btf_vmlinux)) { + if (IS_ERR_OR_NULL(btf_vmlinux)) { bpf_log(log, "btf_vmlinux is malformed\n");
Can you please split IS_ERR and NULL cases and emit different messages to log? If the kernel is not built with btf_vmlinux, saying that it's "malformed" will confuse people. Thanks.
return -EINVAL;
}
--
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