| Message ID | 20200714180904.277512-1-yepeilin.cs@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [Linux-kernel-mentees,v3] bpf: Fix NULL pointer dereference in __btf_resolve_helper_id() | expand |
On 7/14/20 8:09 PM, Peilin Ye wrote: > 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+ee09bda7017345f1fbe6@syzkaller.appspotmail.com > Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com> Looks good, applied, thanks! As far as I can tell all the other occurrences are gated behind btf_parse_vmlinux() where we also init struct_opts, etc. So for bpf-next this would then end up looking like ... int btf_resolve_helper_id(struct bpf_verifier_log *log, const struct bpf_func_proto *fn, int arg) { int id; if (fn->arg_type[arg] != ARG_PTR_TO_BTF_ID) return -EINVAL; id = fn->btf_id[arg]; if (!id || !btf_vmlinux || id > btf_vmlinux->nr_types) return -EINVAL; return id; } > --- > Sorry, I got the link wrong. Thank you for pointing that out. > > Change in v3: > - Fix incorrect syzbot dashboard link. > > 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; >
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;
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+ee09bda7017345f1fbe6@syzkaller.appspotmail.com Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com> --- Sorry, I got the link wrong. Thank you for pointing that out. Change in v3: - Fix incorrect syzbot dashboard link. Change in v2: - Split NULL and IS_ERR cases. kernel/bpf/btf.c | 5 +++++ 1 file changed, 5 insertions(+)