Patch "[PATCH stable/4.14 03/14] bpf, s390x: do not reload skb pointers in non-skb context" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    [PATCH stable/4.14 03/14] bpf, s390x: 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-s390x-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@vger.kernel.org> know about it.


>From foo@baz Fri Dec 22 16:47:02 CET 2017
From: Daniel Borkmann <daniel@iogearbox.net>
Date: Fri, 22 Dec 2017 16:23:01 +0100
Subject: [PATCH stable/4.14 03/14] bpf, s390x: do not reload skb pointers in non-skb context
To: gregkh@linuxfoundation.org
Cc: ast@kernel.org, daniel@iogearbox.net, jannh@google.com, stable@vger.kernel.org, Michael Holzheu <holzheu@linux.vnet.ibm.com>
Message-ID: <20171222152312.2945-4-daniel@iogearbox.net>

From: Daniel Borkmann <daniel@iogearbox.net>


[ Upstream commit 6d59b7dbf72ed20d0138e2f9b75ca3d4a9d4faca ]

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
BPF 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 only. Tested on s390x.

Fixes: 9db7f2b81880 ("s390/bpf: recache skb->data/hlen for skb_vlan_push/pop")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/s390/net/bpf_jit_comp.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -55,8 +55,7 @@ struct bpf_jit {
 #define SEEN_LITERAL	8	/* code uses literals */
 #define SEEN_FUNC	16	/* calls C functions */
 #define SEEN_TAIL_CALL	32	/* code uses tail calls */
-#define SEEN_SKB_CHANGE	64	/* code changes skb data */
-#define SEEN_REG_AX	128	/* code uses constant blinding */
+#define SEEN_REG_AX	64	/* code uses constant blinding */
 #define SEEN_STACK	(SEEN_FUNC | SEEN_MEM | SEEN_SKB)
 
 /*
@@ -448,12 +447,12 @@ static void bpf_jit_prologue(struct bpf_
 			EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0,
 				      REG_15, 152);
 	}
-	if (jit->seen & SEEN_SKB)
+	if (jit->seen & SEEN_SKB) {
 		emit_load_skb_data_hlen(jit);
-	if (jit->seen & SEEN_SKB_CHANGE)
 		/* stg %b1,ST_OFF_SKBP(%r0,%r15) */
 		EMIT6_DISP_LH(0xe3000000, 0x0024, BPF_REG_1, REG_0, REG_15,
 			      STK_OFF_SKBP);
+	}
 }
 
 /*
@@ -983,8 +982,8 @@ static noinline int bpf_jit_insn(struct
 		EMIT2(0x0d00, REG_14, REG_W1);
 		/* lgr %b0,%r2: load return value into %b0 */
 		EMIT4(0xb9040000, BPF_REG_0, REG_2);
-		if (bpf_helper_changes_pkt_data((void *)func)) {
-			jit->seen |= SEEN_SKB_CHANGE;
+		if ((jit->seen & SEEN_SKB) &&
+		    bpf_helper_changes_pkt_data((void *)func)) {
 			/* lg %b1,ST_OFF_SKBP(%r15) */
 			EMIT6_DISP_LH(0xe3000000, 0x0004, BPF_REG_1, REG_0,
 				      REG_15, STK_OFF_SKBP);


Patches currently in stable-queue which might be from daniel@iogearbox.net 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