GCC reported an out of bounds array access when compiling with -O2:
controller/pinctrl.c: In function ‘pinctrl_handle_icmp’:
controller/pinctrl.c:1673:9: error: ‘memcpy’ offset [0, 19] is out of the
bounds [0, 0] [-Werror=array-bounds]
1673 | memcpy(data, in_ip, in_ip_len);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GCC version is: 11.2.1 20210728 (Red Hat 11.2.1-1) (GCC)
This happens because the compiler cannot infer that in this specific
case dp_packet_l4(&packet) can never return NULL.
pinctrl_compose_ipv4() calls eth_compose() which calls
dp_packet_set_l3() and always sets 'l4_ofs' to a value that's different
from UINT16_MAX.
Help the compiler out by asserting that the L4 data is not NULL.
Simplified code sample shared on the gcc-help mailing list:
https://gcc.gnu.org/pipermail/gcc-help/2022-January/141160.html
Reported-by: Ihar Hrachyshka <[email protected]>
Tested-by: Lorenzo Bianconi <[email protected]>
Signed-off-by: Dumitru Ceara <[email protected]>
---
controller/pinctrl.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/controller/pinctrl.c b/controller/pinctrl.c
index d2bb7f441..71a12e8b0 100644
--- a/controller/pinctrl.c
+++ b/controller/pinctrl.c
@@ -1666,6 +1666,12 @@ pinctrl_handle_icmp(struct rconn *swconn, const struct
flow *ip_flow,
}
struct icmp_header *ih = dp_packet_l4(&packet);
+
+ /* The packet's L4 data was allocated and will never be NULL, inform
+ * the compiler about that.
+ */
+ ovs_assert(ih);
+
packet_set_icmp(&packet, ICMP4_DST_UNREACH, icmp_code);
/* Include original IP + data. */
--
2.27.0
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