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+/*
+ * Test that shmat() does not break /proc/self/maps.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include <assert.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <unistd.h>
+
+int main(void)
+{
+ char buf[128];
+ int err, fd;
+ int shmid;
+ ssize_t n;
+ void *p;
+
+ shmid = shmget(IPC_PRIVATE, 1, IPC_CREAT | 0600);
+ assert(shmid != -1);
+
+ /*
+ * The original bug required a non-NULL address, which skipped the
+ * mmap_find_vma step, which could result in a host mapping smaller
+ * than the target mapping. Choose an address at random.
+ */
+ p = shmat(shmid, (void *)0x800000, SHM_RND);
+ if (p == (void *)-1) {
+ /*
+ * Because we are now running the testcase for all guests for which
+ * we have a cross-compiler, the above random address might conflict
+ * with the guest executable in some way. Rather than stopping,
+ * continue with a system supplied address, which should never fail.
+ */
+ p = shmat(shmid, NULL, 0);
+ assert(p != (void *)-1);
+ }
+
+ fd = open("/proc/self/maps", O_RDONLY);
+ assert(fd != -1);
+ do {
+ n = read(fd, buf, sizeof(buf));
+ assert(n >= 0);
+ } while (n != 0);
+ close(fd);
+
+ err = shmdt(p);
+ assert(err == 0);
+ err = shmctl(shmid, IPC_RMID, NULL);
+ assert(err == 0);
+
+ return EXIT_SUCCESS;
+}