6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
[ Upstream commit 06d686f771ddc27a8554cd8f5b22e071040dc90e ]
The kfunc code to handle KF_ARG_PTR_TO_CALLBACK does not check the reg
type before using reg->subprogno. This can accidently permit invalid
pointers from being passed into callback helpers (e.g. silently from
different paths). Likewise, reg->subprogno from the per-register type
union may not be meaningful either. We need to reject any other type
except PTR_TO_FUNC.
Acked-by: Dave Marchevsky <davemarchevsky@xxxxxx>
Fixes: 5d92ddc3de1b ("bpf: Add callback validation to kfunc verifier logic")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230912233214.1518551-14-memxor@xxxxxxxxx
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/bpf/verifier.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 9f180ae74e492..82c9e5c470319 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11202,6 +11202,10 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
break;
}
case KF_ARG_PTR_TO_CALLBACK:
+ if (reg->type != PTR_TO_FUNC) {
+ verbose(env, "arg%d expected pointer to func\n", i);
+ return -EINVAL;
+ }
meta->subprogno = reg->subprogno;
break;
case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
--
2.42.0
