This is a note to let you know that I've just added the patch titled
[PATCH stable/4.14 04/14] bpf, ppc64: do not reload skb pointers in non-skb context
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-ppc64-do-not-reload-skb-pointers-in-non-skb-context.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Fri Dec 22 16:47:02 CET 2017
From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Date: Fri, 22 Dec 2017 16:23:02 +0100
Subject: [PATCH stable/4.14 04/14] bpf, ppc64: do not reload skb pointers in non-skb context
To: gregkh@xxxxxxxxxxxxxxxxxxx
Cc: ast@xxxxxxxxxx, daniel@xxxxxxxxxxxxx, jannh@xxxxxxxxxx, stable@xxxxxxxxxxxxxxx
Message-ID: <20171222152312.2945-5-daniel@xxxxxxxxxxxxx>
From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
[ Upstream commit 87338c8e2cbb317b5f757e6172f94e2e3799cd20 ]
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@xxxxxxxxxxxxx>
Reviewed-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Tested-by: Sandipan Das <sandipan@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/net/bpf_jit_comp64.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -762,7 +762,8 @@ emit_clear:
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);
@@ -771,7 +772,8 @@ emit_clear:
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);
Patches currently in stable-queue which might be from daniel@xxxxxxxxxxxxx are
queue-4.14/bpf-fix-integer-overflows.patch
queue-4.14/bpf-fix-branch-pruning-logic.patch
queue-4.14/bpf-s390x-do-not-reload-skb-pointers-in-non-skb-context.patch
queue-4.14/bpf-sparc-fix-usage-of-wrong-reg-for-load_skb_regs-after-call.patch
queue-4.14/bpf-fix-incorrect-tracking-of-register-size-truncation.patch
queue-4.14/bpf-don-t-prune-branches-when-a-scalar-is-replaced-with-a-pointer.patch
queue-4.14/bpf-verifier-fix-bounds-calculation-on-bpf_rsh.patch
queue-4.14/selftests-bpf-add-tests-for-recent-bugfixes.patch
queue-4.14/bpf-fix-corruption-on-concurrent-perf_event_output-calls.patch
queue-4.14/bpf-fix-incorrect-sign-extension-in-check_alu_op.patch
queue-4.14/bpf-ppc64-do-not-reload-skb-pointers-in-non-skb-context.patch
queue-4.14/bpf-fix-missing-error-return-in-check_stack_boundary.patch
queue-4.14/bpf-force-strict-alignment-checks-for-stack-pointers.patch
queue-4.14/bpf-fix-32-bit-alu-op-verification.patch
queue-4.14/bpf-fix-build-issues-on-um-due-to-mising-bpf_perf_event.h.patch