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authorDavid S. Miller <davem@davemloft.net>2017-05-22 12:27:07 -0400
committerDavid S. Miller <davem@davemloft.net>2017-05-22 12:27:07 -0400
commite4eda884db7930cee434828759064b4711604078 (patch)
treeb4a5875c74a19036e863ac1be67fab65fbd28c09
parent751da2a69b7cc82d83dc310ed7606225f2d6e014 (diff)
net: Make IP alignment calulations clearer.
The assignmnet: ip_align = strict ? 2 : NET_IP_ALIGN; in compare_pkt_ptr_alignment() trips up Coverity because we can only get to this code when strict is true, therefore ip_align will always be 2 regardless of NET_IP_ALIGN's value. So just assign directly to '2' and explain the situation in the comment above. Reported-by: "Gustavo A. R. Silva" <garsilva@embeddedor.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--kernel/bpf/verifier.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1eddb713b815..c72cd41f5b8b 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -808,11 +808,15 @@ static int check_pkt_ptr_alignment(const struct bpf_reg_state *reg,
reg_off += reg->aux_off;
}
- /* skb->data is NET_IP_ALIGN-ed, but for strict alignment checking
- * we force this to 2 which is universally what architectures use
- * when they don't set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS.
+ /* For platforms that do not have a Kconfig enabling
+ * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
+ * NET_IP_ALIGN is universally set to '2'. And on platforms
+ * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
+ * to this code only in strict mode where we want to emulate
+ * the NET_IP_ALIGN==2 checking. Therefore use an
+ * unconditional IP align value of '2'.
*/
- ip_align = strict ? 2 : NET_IP_ALIGN;
+ ip_align = 2;
if ((ip_align + reg_off + off) % size != 0) {
verbose("misaligned packet access off %d+%d+%d size %d\n",
ip_align, reg_off, off, size);