From a2ebe1c6dc5f4cd2dc7233ebad597d1c6cf370bf Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Mon, 18 May 2020 15:05:27 +0200 Subject: [PATCH] BACKPORT: bpf: Fix too large copy from user in bpf_test_init Commit bc56c919fce7 ("bpf: Add xdp.frame_sz in bpf_prog_test_run_xdp().") recently changed bpf_prog_test_run_xdp() to use larger frames for XDP in order to test tail growing frames (via bpf_xdp_adjust_tail) and to have memory backing frame better resemble drivers. The commit contains a bug, as it tries to copy the max data size from userspace, instead of the size provided by userspace. This cause XDP unit tests to fail sporadically with EFAULT, an unfortunate behavior. The fix is to only copy the size specified by userspace. Fixes: bc56c919fce7 ("bpf: Add xdp.frame_sz in bpf_prog_test_run_xdp().") Change-Id: Icaa7422f649c08524dc8cc443678c79c6dde794b Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/158980712729.256597.6115007718472928659.stgit@firesoul --- net/bpf/test_run.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 04c7aa130f26..0afc3b13ba5e 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -160,17 +160,21 @@ static void *bpf_test_init(const union bpf_attr *kattr, u32 size, u32 headroom, u32 tailroom) { void __user *data_in = u64_to_user_ptr(kattr->test.data_in); + u32 user_size = kattr->test.data_size_in; void *data; if (size < ETH_HLEN || size > PAGE_SIZE - headroom - tailroom) return ERR_PTR(-EINVAL); + if (user_size > size) + return ERR_PTR(-EMSGSIZE); + size = SKB_DATA_ALIGN(size); data = kzalloc(size + headroom + tailroom, GFP_USER); if (!data) return ERR_PTR(-ENOMEM); - if (copy_from_user(data + headroom, data_in, size)) { + if (copy_from_user(data + headroom, data_in, user_size)) { kfree(data); return ERR_PTR(-EFAULT); } @@ -487,8 +491,6 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr, /* XDP have extra tailroom as (most) drivers use full page */ max_data_sz = 4096 - headroom - tailroom; - if (size > max_data_sz) - return -EINVAL; data = bpf_test_init(kattr, max_data_sz, headroom, tailroom); if (IS_ERR(data))