linux: Update the mremap C implementation [BZ #31968]

Update the mremap C implementation to support the optional argument for MREMAP_DONTUNMAP added in Linux 5.7 since it may not always be correct to implement a variadic function as a non-variadic function on all Linux targets. Return MAP_FAILED and set errno to EINVAL for unknown flag bits. This fixes BZ #31968. Note: A test must be added when a new flag bit is introduced. Signed-off-by: H.J. Lu <[email protected]> Reviewed-by: Adhemerval Zanella <[email protected]>
ahjragaas · Aug 1, 2024 · 6c40cb0 · 6c40cb0
1 parent 5425239
commit 6c40cb0
Showing 1 changed file with 13 additions and 1 deletion.
diff --git a/sysdeps/unix/sysv/linux/mremap.c b/sysdeps/unix/sysv/linux/mremap.c
@@ -20,14 +20,26 @@
 #include <sysdep.h>
 #include <stdarg.h>
 #include <stddef.h>
+#include <errno.h>
+
+#define MREMAP_KNOWN_BITS \
+  (MREMAP_MAYMOVE \
+   | MREMAP_FIXED \
+   | MREMAP_DONTUNMAP)
 
 void *
 __mremap (void *addr, size_t old_len, size_t new_len, int flags, ...)
 {
   va_list va;
   void *new_addr = NULL;
 
-  if (flags & MREMAP_FIXED)
+  if (flags & ~(MREMAP_KNOWN_BITS))
+    {
+      __set_errno (EINVAL);
+      return MAP_FAILED;
+    }
+
+  if (flags & (MREMAP_FIXED | MREMAP_DONTUNMAP))
     {
       va_start (va, flags);
       new_addr = va_arg (va, void *);