s390/bpf: fix recache skb->data/hlen for skb_vlan_push/pop

commit 6edf0aa4f8bbdfbb4d6d786892fa02728d05dc36 upstream.

In case of usage of skb_vlan_push/pop, in the prologue we store
the SKB pointer on the stack and restore it after BPF_JMP_CALL
to skb_vlan_push/pop.

Unfortunately currently there are two bugs in the code:

 1) The wrong stack slot (offset 170 instead of 176) is used
 2) The wrong register (W1 instead of B1) is saved

So fix this and use correct stack slot and register.

Fixes: 9db7f2b81880 ("s390/bpf: recache skb->data/hlen for skb_vlan_push/pop")
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/s390/net/bpf_jit.h b/arch/s390/net/bpf_jit.h
index f010c93a88b16c1d909069c14237ff389fa759df..fda605dbc1b44b08e62f30b15b1d4d6b6283cbb3 100644 (file)
--- a/arch/s390/net/bpf_jit.h
+++ b/arch/s390/net/bpf_jit.h
@@ -37,7 +37,7 @@ extern u8 sk_load_word[], sk_load_half[], sk_load_byte[];
  *           |               |     |
  *           +---------------+     |
  *           | 8 byte skbp   |     |
- * R15+170 -> +---------------+     |
+ * R15+176 -> +---------------+     |
  *           | 8 byte hlen   |     |
  * R15+168 -> +---------------+     |
  *           | 4 byte align  |     |
@@ -58,7 +58,7 @@ extern u8 sk_load_word[], sk_load_half[], sk_load_byte[];
 #define STK_OFF                (STK_SPACE - STK_160_UNUSED)
 #define STK_OFF_TMP    160     /* Offset of tmp buffer on stack */
 #define STK_OFF_HLEN   168     /* Offset of SKB header length on stack */
-#define STK_OFF_SKBP   170     /* Offset of SKB pointer on stack */
+#define STK_OFF_SKBP   176     /* Offset of SKB pointer on stack */
 
 #define STK_OFF_R6     (160 - 11 * 8)  /* Offset of r6 on stack */
 #define STK_OFF_TCCNT  (160 - 12 * 8)  /* Offset of tail_call_cnt on stack */

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 9a0c4c22e53670b1d813f3ddfb328b76c8e06c78..fe607c8d25d236308f16485323b002e31026e83b 100644 (file)
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -446,7 +446,7 @@ static void bpf_jit_prologue(struct bpf_jit *jit, bool is_classic)
                emit_load_skb_data_hlen(jit);
        if (jit->seen & SEEN_SKB_CHANGE)
                /* stg %b1,ST_OFF_SKBP(%r0,%r15) */
-               EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0, REG_15,
+               EMIT6_DISP_LH(0xe3000000, 0x0024, BPF_REG_1, REG_0, REG_15,
                              STK_OFF_SKBP);
        /* Clear A (%b0) and X (%b7) registers for converted BPF programs */
        if (is_classic) {