From: Yi Zhang yi.zhang@redhat.com
commit 60b1af64eb35074a4f2d41cc1e503a7671e68963 upstream.
'parent' sysfs reads will yield '\0' bytes when the interface name has 15 chars, and there will no "\n" output.
To reproduce, create one interface with 15 chars:
[root@test ~]# ip a s enp0s29u1u7u3c2 2: enp0s29u1u7u3c2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 1000 link/ether 02:21:28:57:47:17 brd ff:ff:ff:ff:ff:ff inet6 fe80::ac41:338f:5bcd:c222/64 scope link noprefixroute valid_lft forever preferred_lft forever [root@test ~]# modprobe rdma_rxe [root@test ~]# echo enp0s29u1u7u3c2 > /sys/module/rdma_rxe/parameters/add [root@test ~]# cat /sys/class/infiniband/rxe0/parent enp0s29u1u7u3c2[root@test ~]# [root@test ~]# f="/sys/class/infiniband/rxe0/parent" [root@test ~]# echo "$(<"$f")" -bash: warning: command substitution: ignored null byte in input enp0s29u1u7u3c2
Use scnprintf and PAGE_SIZE to fill the sysfs output buffer.
Cc: stable@vger.kernel.org Fixes: 8700e3e7c485 ("Soft RoCE driver") Link: https://lore.kernel.org/r/20200820153646.31316-1-yi.zhang@redhat.com Suggested-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Yi Zhang yi.zhang@redhat.com Reviewed-by: Bart Van Assche bvanassche@acm.org Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/infiniband/sw/rxe/rxe_verbs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/infiniband/sw/rxe/rxe_verbs.c +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c @@ -1178,7 +1178,7 @@ static ssize_t parent_show(struct device struct rxe_dev *rxe = container_of(device, struct rxe_dev, ib_dev.dev);
- return snprintf(buf, 16, "%s\n", rxe_parent_name(rxe, 1)); + return scnprintf(buf, PAGE_SIZE, "%s\n", rxe_parent_name(rxe, 1)); }
static DEVICE_ATTR_RO(parent);