[PATCH iwl-next v3] ixgbe: fix unaligned u32 access in ixgbe_update_flash_X550()

[Aleksandr Loktionov <aleksandr.loktionov@intel.com>]

ixgbe_host_interface_command() treats its buffer as a u32 array. The 
local buffer we pass in was a union of byte-sized fields, which gives 
it 1-byte alignment on the stack. On strict-align architectures this 
can cause unaligned 32-bit accesses.

Add a u32 member to union ixgbe_hic_hdr2 so the object is 4-byte 
aligned, and pass the u32 member when calling
ixgbe_host_interface_command().

No functional change on x86; prevents unaligned accesses on 
architectures that enforce natural alignment.
 
Fixes: 49425dfc7451 ("ixgbe: Add support for x550em_a 10G MAC type")
Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
---
v2 -> v3 commit message line wraps
v1 -> v2 change title and concentrate on alignement issue
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_type.h | 1 +
 drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
index 61f2ef6..eb5bf3b 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
@@ -2798,6 +2798,7 @@ struct ixgbe_hic_hdr2_rsp {
 };
 
 union ixgbe_hic_hdr2 {
+	u32 buf[1];
 	struct ixgbe_hic_hdr2_req req;
 	struct ixgbe_hic_hdr2_rsp rsp;
 };
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c
index 76d2fa3..4a0ccbf 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c
@@ -1228,7 +1228,7 @@ static int ixgbe_update_flash_X550(struct ixgbe_hw *hw)
 	buffer.req.buf_lenl = FW_SHADOW_RAM_DUMP_LEN;
 	buffer.req.checksum = FW_DEFAULT_CHECKSUM;
 
-	status = ixgbe_host_interface_command(hw, &buffer, sizeof(buffer),
+	status = ixgbe_host_interface_command(hw, buffer.buf, sizeof(buffer),
 					      IXGBE_HI_COMMAND_TIMEOUT, false);
 	return status;
 }
-- 
2.52.0