6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Daniel Borkmann daniel@iogearbox.net
[ Upstream commit f9bb6ffa7f5ad0f8ee0f53fc4a10655872ee4a14 ]
Stanislav reported that in bpf_crypto_crypt() the destination dynptr's size is not validated to be at least as large as the source dynptr's size before calling into the crypto backend with 'len = src_len'. This can result in an OOB write when the destination is smaller than the source.
Concretely, in mentioned function, psrc and pdst are both linear buffers fetched from each dynptr:
psrc = __bpf_dynptr_data(src, src_len); [...] pdst = __bpf_dynptr_data_rw(dst, dst_len); [...] err = decrypt ? ctx->type->decrypt(ctx->tfm, psrc, pdst, src_len, piv) : ctx->type->encrypt(ctx->tfm, psrc, pdst, src_len, piv);
The crypto backend expects pdst to be large enough with a src_len length that can be written. Add an additional src_len > dst_len check and bail out if it's the case. Note that these kfuncs are accessible under root privileges only.
Fixes: 3e1c6f35409f ("bpf: make common crypto API for TC/XDP programs") Reported-by: Stanislav Fort disclosure@aisle.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Cc: Vadim Fedorenko vadim.fedorenko@linux.dev Reviewed-by: Vadim Fedorenko vadim.fedorenko@linux.dev Link: https://lore.kernel.org/r/20250829143657.318524-1-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/crypto.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/crypto.c b/kernel/bpf/crypto.c index 94854cd9c4cc3..83c4d9943084b 100644 --- a/kernel/bpf/crypto.c +++ b/kernel/bpf/crypto.c @@ -278,7 +278,7 @@ static int bpf_crypto_crypt(const struct bpf_crypto_ctx *ctx, siv_len = siv ? __bpf_dynptr_size(siv) : 0; src_len = __bpf_dynptr_size(src); dst_len = __bpf_dynptr_size(dst); - if (!src_len || !dst_len) + if (!src_len || !dst_len || src_len > dst_len) return -EINVAL;
if (siv_len != ctx->siv_len)