[dpdk-dev] [PATCH] net/i40e: fix build for 32-bit

[Ferruh Yigit]

Got error with: gcc 11.2.1 "cc (GCC) 11.2.1 20210728 (Red Hat 11.2.1-1)"

Build error:
In function ‘i40e_flow_parse_fdir_pattern’,
    inlined from ‘i40e_flow_parse_fdir_filter’
    at ../drivers/net/i40e/i40e_flow.c:3274:8:
../drivers/net/i40e/i40e_flow.c:3052:69:
    error: writing 1 byte into a region of size 0
    [-Werror=stringop-overflow=]
 3052 |                         filter->input.flow_ext.flexbytes[j] =
      |                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
 3053 |                                 raw_spec->pattern[i];
      |                                 ~~~~~~~~~~~~~~~~~~~~
In file included from ../drivers/net/i40e/i40e_flow.c:25:
  ../drivers/net/i40e/i40e_flow.c:
  In function ‘i40e_flow_parse_fdir_filter’:
  ../drivers/net/i40e/i40e_ethdev.h:638:17:
  note: at offset 16 into destination object ‘flexbytes’ of size 16
  638 |         uint8_t flexbytes[RTE_ETH_FDIR_MAX_FLEXLEN];
      |                 ^~~~~~~~~

Fixing by adding range checks.

Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>
---
Cc: Qi Z Zhang <qi.z.zhang at intel.com>

Not sure why only 32-bit is causing this error, or if the overflow
practically can occurs.

./devtools/test-meson-builds.sh is not catching the warning because of
'--buildtype=debugoptimized'.

I can reproduce in my environment as following:
PKG_CONFIG_LIBDIR=/usr/lib/pkgconfig meson --werror -Dc_args=-m32
-Dc_link_args=-m32 build && ninja -C build
---
 drivers/net/i40e/i40e_flow.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/i40e/i40e_flow.c b/drivers/net/i40e/i40e_flow.c
index 9acaa1875105..c9676caab5dd 100644
--- a/drivers/net/i40e/i40e_flow.c
+++ b/drivers/net/i40e/i40e_flow.c
@@ -3049,6 +3049,9 @@ i40e_flow_parse_fdir_pattern(struct rte_eth_dev *dev,
 
 			for (i = 0; i < raw_spec->length; i++) {
 				j = i + next_dst_off;
+				if (j >= RTE_ETH_FDIR_MAX_FLEXLEN ||
+						j >= I40E_FDIR_MAX_FLEX_LEN)
+					break;
 				filter->input.flow_ext.flexbytes[j] =
 					raw_spec->pattern[i];
 				filter->input.flow_ext.flex_mask[j] =
-- 
2.31.1