The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 60b1af64eb35074a4f2d41cc1e503a7671e68963 Mon Sep 17 00:00:00 2001

From: Yi Zhang yi.zhang@redhat.com Date: Thu, 20 Aug 2020 23:36:46 +0800 Subject: [PATCH] RDMA/rxe: Fix the parent sysfs read when the interface has 15 chars

'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

diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c index bb61e534e468..756980f79951 100644 --- a/drivers/infiniband/sw/rxe/rxe_verbs.c +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c @@ -1056,7 +1056,7 @@ static ssize_t parent_show(struct device *device, struct rxe_dev *rxe = rdma_device_to_drv_device(device, struct rxe_dev, ib_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);