@@ -763,7 +763,8 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
func = (u8 *) __bpf_call_base + imm;
/* Save skb pointer if we need to re-cache skb data */
- if (bpf_helper_changes_pkt_data(func))
+ if ((ctx->seen & SEEN_SKB) &&
+ bpf_helper_changes_pkt_data(func))
PPC_BPF_STL(3, 1, bpf_jit_stack_local(ctx));
bpf_jit_emit_func_call(image, ctx, (u64)func);
@@ -772,7 +773,8 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
PPC_MR(b2p[BPF_REG_0], 3);
/* refresh skb cache */
- if (bpf_helper_changes_pkt_data(func)) {
+ if ((ctx->seen & SEEN_SKB) &&
+ bpf_helper_changes_pkt_data(func)) {
/* reload skb pointer to r3 */
PPC_BPF_LL(3, 1, bpf_jit_stack_local(ctx));
bpf_jit_emit_skb_loads(image, ctx);
The assumption of unconditionally reloading skb pointers on BPF helper calls where bpf_helper_changes_pkt_data() holds true is wrong. There can be different contexts where the helper would enforce a reload such as in case of XDP. Here, we do have a struct xdp_buff instead of struct sk_buff as context, thus this will access garbage. JITs only ever need to deal with cached skb pointer reload when ld_abs/ind was seen, therefore guard the reload behind SEEN_SKB. Fixes: 156d0e290e96 ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Tested-by: Sandipan Das <sandipan@linux.vnet.ibm.com> --- arch/powerpc/net/bpf_jit_comp64.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)