From: Jakub Sitnicki jakub@cloudflare.com
[ Upstream commit 436864095a95fcc611c20c44a111985fa9848730 ]
Data passed to user-space with a (SOL_UDP, UDP_GRO) cmsg carries an int (see udp_cmsg_recv), not a u16 value, as strace confirms:
recvmsg(8, {msg_name=..., msg_iov=[{iov_base="\0\0..."..., iov_len=96000}], msg_iovlen=1, msg_control=[{cmsg_len=20, <-- sizeof(cmsghdr) + 4 cmsg_level=SOL_UDP, cmsg_type=0x68}], <-- UDP_GRO msg_controllen=24, msg_flags=0}, 0) = 11200
Interpreting the data as an u16 value won't work on big-endian platforms. Since it is too late to back out of this API decision [1], fix the test.
[1]: https://lore.kernel.org/netdev/20230131174601.203127-1-jakub@cloudflare.com/
Fixes: 3327a9c46352 ("selftests: add functionals test for UDP GRO") Suggested-by: Eric Dumazet edumazet@google.com Signed-off-by: Jakub Sitnicki jakub@cloudflare.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/net/udpgso_bench_rx.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/net/udpgso_bench_rx.c b/tools/testing/selftests/net/udpgso_bench_rx.c index 4058c7451e70d..f35a924d4a303 100644 --- a/tools/testing/selftests/net/udpgso_bench_rx.c +++ b/tools/testing/selftests/net/udpgso_bench_rx.c @@ -214,11 +214,10 @@ static void do_verify_udp(const char *data, int len)
static int recv_msg(int fd, char *buf, int len, int *gso_size) { - char control[CMSG_SPACE(sizeof(uint16_t))] = {0}; + char control[CMSG_SPACE(sizeof(int))] = {0}; struct msghdr msg = {0}; struct iovec iov = {0}; struct cmsghdr *cmsg; - uint16_t *gsosizeptr; int ret;
iov.iov_base = buf; @@ -237,8 +236,7 @@ static int recv_msg(int fd, char *buf, int len, int *gso_size) cmsg = CMSG_NXTHDR(&msg, cmsg)) { if (cmsg->cmsg_level == SOL_UDP && cmsg->cmsg_type == UDP_GRO) { - gsosizeptr = (uint16_t *) CMSG_DATA(cmsg); - *gso_size = *gsosizeptr; + *gso_size = *(int *)CMSG_DATA(cmsg); break; } }