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SUNRPC: lock against ->sock changing during sysfs read

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->sock can be set to NULL asynchronously unless ->recv_mutex is held.
So it is important to hold that mutex.  Otherwise a sysfs read can
trigger an oops.
Commit 17f09d3f61 ("SUNRPC: Check if the xprt is connected before
handling sysfs reads") appears to attempt to fix this problem, but it
only narrows the race window.

Fixes: 17f09d3f61 ("SUNRPC: Check if the xprt is connected before handling sysfs reads")
Fixes: a8482488a7 ("SUNRPC query transport's source port")
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
NeilBrown 2022-01-17 16:36:53 +11:00 committed by Anna Schumaker
parent 63db37e99a
commit b49ea673e1
2 changed files with 10 additions and 2 deletions
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5
net/sunrpc/sysfs.c
View File

@ -115,11 +115,14 @@ static ssize_t rpc_sysfs_xprt_srcaddr_show(struct kobject *kobj,
}
sock = container_of(xprt, struct sock_xprt, xprt);
if (kernel_getsockname(sock->sock, (struct sockaddr *)&saddr) < 0)
mutex_lock(&sock->recv_mutex);
if (sock->sock == NULL ||
kernel_getsockname(sock->sock, (struct sockaddr *)&saddr) < 0)
goto out;
ret = sprintf(buf, "%pISc\n", &saddr);
out:
mutex_unlock(&sock->recv_mutex);
xprt_put(xprt);
return ret + 1;
}

7
net/sunrpc/xprtsock.c
View File

@ -1641,7 +1641,12 @@ static int xs_get_srcport(struct sock_xprt *transport)
unsigned short get_srcport(struct rpc_xprt *xprt)
{
struct sock_xprt *sock = container_of(xprt, struct sock_xprt, xprt);
return xs_sock_getport(sock->sock);
unsigned short ret = 0;
mutex_lock(&sock->recv_mutex);
if (sock->sock)
ret = xs_sock_getport(sock->sock);
mutex_unlock(&sock->recv_mutex);
return ret;
}
EXPORT_SYMBOL(get_srcport);