sysvipc: Return EINVAL for invalid shmctl commands

It avoids regressions on possible future commands that might require
additional libc support.  The downside is new commands added by newer
kernels will need further glibc support.

Checked on x86_64-linux-gnu and i686-linux-gnu (Linux v4.15 and v5.4).

3 files changed, 69 insertions, 13 deletions

diff --git a/sysdeps/unix/sysv/linux/shmctl.c b/sysdeps/unix/sysv/linux/shmctl.c
index 1d19a798b1..833f013e69 100644
--- a/sysdeps/unix/sysv/linux/shmctl.c
+++ b/sysdeps/unix/sysv/linux/shmctl.c
@@ -88,25 +88,49 @@ __shmctl64 (int shmid, int cmd, struct __shmid64_ds *buf)
 {
 #if __IPC_TIME64
   struct kernel_shmid64_ds kshmid, *arg = NULL;
-  if (buf != NULL)
+#else
+  shmctl_arg_t *arg;
+#endif
+
+  switch (cmd)
     {
-      /* This is a Linux extension where kernel expects either a
-	 'struct shminfo' (IPC_INFO) or 'struct shm_info' (SHM_INFO).  */
-      if (cmd == IPC_INFO || cmd == SHM_INFO)
-	arg = (struct kernel_shmid64_ds *) buf;
-      else
+    case IPC_RMID:
+    case SHM_LOCK:
+    case SHM_UNLOCK:
+      arg = NULL;
+      break;
+
+    case IPC_SET:
+    case IPC_STAT:
+    case SHM_STAT:
+    case SHM_STAT_ANY:
+#if __IPC_TIME64
+      if (buf != NULL)
 	{
 	  shmid64_to_kshmid64 (buf, &kshmid);
 	  arg = &kshmid;
 	}
-    }
 # ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
-  if (cmd == IPC_SET)
-    arg->shm_perm.mode *= 0x10000U;
+      if (cmd == IPC_SET)
+        arg->shm_perm.mode *= 0x10000U;
 # endif
 #else
-  shmctl_arg_t *arg = buf;
+      arg = buf;
 #endif
+      break;
+
+    case IPC_INFO:
+    case SHM_INFO:
+      /* This is a Linux extension where kernel expects either a
+	 'struct shminfo' (IPC_INFO) or 'struct shm_info' (SHM_INFO).  */
+      arg = (__typeof__ (arg)) buf;
+      break;
+
+    default:
+      __set_errno (EINVAL);
+      return -1;
+    }
+
 
   int ret = shmctl_syscall (shmid, cmd, arg);
   if (ret < 0)
diff --git a/sysvipc/test-sysvipc.h b/sysvipc/test-sysvipc.h
index 21ef6c6565..d1c8349b45 100644
--- a/sysvipc/test-sysvipc.h
+++ b/sysvipc/test-sysvipc.h
@@ -25,7 +25,7 @@
 #include <sys/shm.h>
 #include <include/array_length.h>
 
-/* Return the first invalid command SysV IPC command from common shared
+/* Return the first invalid SysV IPC command from common shared
    between message queue, shared memory, and semaphore.  */
 static inline int
 first_common_invalid_cmd (void)
@@ -50,7 +50,7 @@ first_common_invalid_cmd (void)
   return invalid;
 }
 
-/* Return the first invalid command SysV IPC command for semaphore.  */
+/* Return the first invalid SysV IPC command for semaphore.  */
 static inline int
 first_sem_invalid_cmd (void)
 {
@@ -82,7 +82,7 @@ first_sem_invalid_cmd (void)
   return invalid;
 }
 
-/* Return the first invalid command SysV IPC command for message queue.  */
+/* Return the first invalid SysV IPC command for message queue.  */
 static inline int
 first_msg_invalid_cmd (void)
 {
@@ -107,4 +107,31 @@ first_msg_invalid_cmd (void)
   return invalid;
 }
 
+/* Return the first invalid SysV IPC command for shared memory.  */
+static inline int
+first_shm_invalid_cmd (void)
+{
+  const int shm_cmds[] = {
+    SHM_STAT,
+    SHM_INFO,
+#ifdef SHM_STAT_ANY
+    SHM_STAT_ANY,
+#endif
+    SHM_LOCK,
+    SHM_UNLOCK
+  };
+
+  int invalid = first_common_invalid_cmd ();
+  for (int i = 0; i < array_length (shm_cmds); i++)
+    {
+      if (invalid == shm_cmds[i])
+	{
+	  invalid++;
+	  i = 0;
+	}
+    }
+
+  return invalid;
+}
+
 #endif /* _TEST_SYSV_H  */
diff --git a/sysvipc/test-sysvshm.c b/sysvipc/test-sysvshm.c
index f083fd280b..a1b8b4823e 100644
--- a/sysvipc/test-sysvshm.c
+++ b/sysvipc/test-sysvshm.c
@@ -25,6 +25,8 @@
 #include <sys/ipc.h>
 #include <sys/shm.h>
 
+#include <test-sysvipc.h>
+
 #include <support/support.h>
 #include <support/check.h>
 #include <support/temp_file.h>
@@ -81,6 +83,9 @@ do_test (void)
       FAIL_EXIT1 ("shmget failed (errno=%d)", errno);
     }
 
+  TEST_COMPARE (shmctl (shmid, first_shm_invalid_cmd (), NULL), -1);
+  TEST_COMPARE (errno, EINVAL);
+
   /* Get shared memory kernel information and do some sanity checks.  */
   struct shmid_ds shminfo;
   if (shmctl (shmid, IPC_STAT, &shminfo) == -1)