Author: hselasky
Date: Tue Dec 22 09:26:24 2015
New Revision: 292592
URL: https://svnweb.freebsd.org/changeset/base/292592
Log:
Guard against the same process being both CUSE server and client at
the same time. This can easily lead to a deadlock when destroying the
character devices nodes.
Modified:
head/sys/fs/cuse/cuse.c
Modified: head/sys/fs/cuse/cuse.c
==============================================================================
--- head/sys/fs/cuse/cuse.c Tue Dec 22 09:08:21 2015 (r292591)
+++ head/sys/fs/cuse/cuse.c Tue Dec 22 09:26:24 2015 (r292592)
@@ -108,6 +108,7 @@ struct cuse_server {
TAILQ_HEAD(, cuse_client) hcli;
struct cv cv;
struct selinfo selinfo;
+ pid_t pid;
int is_closing;
int refs;
};
@@ -691,6 +692,10 @@ cuse_server_open(struct cdev *dev, int f
free(pcs, M_CUSE);
return (ENOMEM);
}
+
+ /* store current process ID */
+ pcs->pid = curproc->p_pid;
+
TAILQ_INIT(&pcs->head);
TAILQ_INIT(&pcs->hdev);
TAILQ_INIT(&pcs->hcli);
@@ -1357,9 +1362,15 @@ cuse_client_open(struct cdev *dev, int f
if (pcsd != NULL) {
pcs = pcsd->server;
pcd = pcsd->user_dev;
+ /*
+ * Check that the refcount didn't wrap and that the
+ * same process is not both client and server. This
+ * can easily lead to deadlocks when destroying the
+ * CUSE character device nodes:
+ */
pcs->refs++;
- if (pcs->refs < 0) {
- /* overflow */
+ if (pcs->refs < 0 || pcs->pid == curproc->p_pid) {
+ /* overflow or wrong PID */
pcs->refs--;
pcsd = NULL;
}
_______________________________________________
svn-src-all@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
