Merge pull request #2 from marler8997/mremapUnderflow

add mremap underflow patch

Author: mikdusan

command/patch

@@ -6,3 +6,4 @@ set -e
 
 WORKDIR "/work/src/${QEMU_SRC_BASENAME}"
 RUN patch -p1 -i "${WORK_ROOT}/patch/${QEMU_NAME}.diff"
+RUN patch -p1 -i "${WORK_ROOT}/patch/mremap-underflow.diff"

patch/mremap-underflow.diff

@@ -0,0 +1,14 @@
+diff --git a/linux-user/mmap.c b/linux-user/mmap.c
+index e378033797..da0fe4cc86 100644
+--- a/linux-user/mmap.c
++++ b/linux-user/mmap.c
+@@ -708,7 +708,8 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size,
+         if (prot == 0) {
+             host_addr = mremap(g2h(old_addr), old_size, new_size, flags);
+             if (host_addr != MAP_FAILED && reserved_va && old_size > new_size) {
+-                mmap_reserve(old_addr + old_size, new_size - old_size);
++                if (new_size > old_size)
++                    mmap_reserve(old_addr + old_size, new_size - old_size);
+             }
+         } else {
+             errno = ENOMEM;