From 49b18315be4eecfc36b75f4aecb4d40a87d68a20 Mon Sep 17 00:00:00 2001 From: KP Singh Date: Wed, 20 May 2026 04:40:59 +0200 Subject: [PATCH] bpf: Reject NULL data/sig in bpf_verify_pkcs7_signature __bpf_dynptr_data() can return NULL (FILE dynptrs, any non-contiguous backing). bpf_verify_pkcs7_signature() forwards the pointer to verify_pkcs7_signature() unchecked, causing a NULL deref in asn1_ber_decoder() reachable from a sleepable BPF LSM at lsm.s/bpf. NULL-check both pointers and reject with -EINVAL. Mirrors the guards already in kernel/bpf/crypto.c. Fixes: 865b0566d8f1 ("bpf: Add bpf_verify_pkcs7_signature() kfunc") Reported-by: Xianrui Dong Signed-off-by: KP Singh Reviewed-by: Amery Hung Acked-by: Song Liu Acked-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20260520024059.313468-1-kpsingh@kernel.org Signed-off-by: Kumar Kartikeya Dwivedi --- kernel/bpf/helpers.c | 5 +++++ tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 2bb60200c266..b5314c9fed3c 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -4241,8 +4241,13 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_p, data_len = __bpf_dynptr_size(data_ptr); data = __bpf_dynptr_data(data_ptr, data_len); + if (!data) + return -EINVAL; + sig_len = __bpf_dynptr_size(sig_ptr); sig = __bpf_dynptr_data(sig_ptr, sig_len); + if (!sig) + return -EINVAL; return verify_pkcs7_signature(data, data_len, sig, sig_len, trusted_keyring->key, diff --git a/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c b/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c index 8cd298b78e44..04aaf4c9cf5e 100644 --- a/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c +++ b/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c @@ -14,7 +14,7 @@ static struct { const char *prog_name; int expected_runtime_err; } kfunc_dynptr_tests[] = { - {"dynptr_data_null", -EBADMSG}, + {"dynptr_data_null", -EINVAL}, }; static bool kfunc_not_supported;