From: Daniel Borkmann daniel@iogearbox.net
commit 0d906b1e8d4002cdd59590fec630f4e75023e288 upstream.
After commit 636c2628086e ("net: skbuff: Remove errornous length validation in skb_vlan_pop()") mentioned test case stopped working, throwing a -12 (ENOMEM) return code. The issue however is not due to 636c2628086e, but rather due to a buggy test case that got uncovered from the change in behaviour in 636c2628086e.
The data_size of that test case for the skb was set to 1. In the bpf_fill_ld_abs_vlan_push_pop() handler bpf insns are generated that loop with: reading skb data, pushing 68 tags, reading skb data, popping 68 tags, reading skb data, etc, in order to force a skb expansion and thus trigger that JITs recache skb->data. Problem is that initial data_size is too small.
While before 636c2628086e, the test silently bailed out due to the skb->len < VLAN_ETH_HLEN check with returning 0, and now throwing an error from failing skb_ensure_writable(). Set at least minimum of ETH_HLEN as an initial length so that on first push of data, equivalent pop will succeed.
Fixes: 4d9c5c53ac99 ("test_bpf: add bpf_skb_vlan_push/pop() tests") Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Alexei Starovoitov ast@kernel.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- lib/test_bpf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/lib/test_bpf.c +++ b/lib/test_bpf.c @@ -4556,7 +4556,7 @@ static struct bpf_test tests[] = { { }, INTERNAL, { 0x34 }, - { { 1, 0xbef } }, + { { ETH_HLEN, 0xbef } }, .fill_helper = bpf_fill_ld_abs_vlan_push_pop, }, /*