If an address range given to `mremap` is invalid (exceeds addressing
bounds on the guest), we were previously returning `ENOMEM`, which is
not correct. The manpage and the Linux kernel implementation both agree
that if `old_addr`/`old_size` refer to an invalid address, `EFAULT` is
returned, and if `new_addr`/`new_size` refer to an invalid address,
`EINVAL` is returned.

Signed-off-by: Matthew Lugg <mlugg@mlugg.co.uk>
---
 linux-user/mmap.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Changes from last revision: the EINVAL case has been moved before the EFAULT
case in accordance with Richard's feedback.

diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index ef3833a2bb..6163f1a0d1 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -1110,12 +1110,15 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size,
     int prot;
     void *host_addr;
 
-    if (!guest_range_valid_untagged(old_addr, old_size) ||
-        ((flags & MREMAP_FIXED) &&
+    if (((flags & MREMAP_FIXED) &&
          !guest_range_valid_untagged(new_addr, new_size)) ||
         ((flags & MREMAP_MAYMOVE) == 0 &&
          !guest_range_valid_untagged(old_addr, new_size))) {
-        errno = ENOMEM;
+        errno = EINVAL;
+        return -1;
+    }
+    if (!guest_range_valid_untagged(old_addr, old_size)) {
+        errno = EFAULT;
         return -1;
     }
 
-- 
2.51.2