diff mbox series

[PULL,01/14] linux-user/mmap.c: check range of mremap result in target address space

Message ID 20201218102407.597566-2-laurent@vivier.eu
State New
Headers show
Series [PULL,01/14] linux-user/mmap.c: check range of mremap result in target address space | expand

Commit Message

Laurent Vivier Dec. 18, 2020, 10:23 a.m. UTC 
From: Tobias Koch <tobias.koch@nonterra.com>

If mremap succeeds, an additional check is performed to ensure that the
new address range fits into the target address space. This check was
previously perfomed in host address space, with the upper bound fixed to
abi_ulong.

This patch replaces the static check with a call to `guest_range_valid`,
performing the range check against the actual size of the target address
space. It also moves the corresponding block to prevent it from being
called incorrectly when the mapping itself fails.

Signed-off-by: Tobias Koch <tobias.koch@nonterra.com>
Message-Id: <20201028213833.26592-1-tobias.koch@nonterra.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/mmap.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)
diff mbox series

Patch

diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 00c05e6a0f19..810653c50357 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -767,20 +767,23 @@  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, old_size - new_size);
+
+            if (host_addr != MAP_FAILED) {
+                /* Check if address fits target address space */
+                if (!guest_range_valid(h2g(host_addr), new_size)) {
+                    /* Revert mremap() changes */
+                    host_addr = mremap(g2h(old_addr), new_size, old_size,
+                                       flags);
+                    errno = ENOMEM;
+                    host_addr = MAP_FAILED;
+                } else if (reserved_va && old_size > new_size) {
+                    mmap_reserve(old_addr + old_size, old_size - new_size);
+                }
             }
         } else {
             errno = ENOMEM;
             host_addr = MAP_FAILED;
         }
-        /* Check if address fits target address space */
-        if ((unsigned long)host_addr + new_size > (abi_ulong)-1) {
-            /* Revert mremap() changes */
-            host_addr = mremap(g2h(old_addr), new_size, old_size, flags);
-            errno = ENOMEM;
-            host_addr = MAP_FAILED;
-        }
     }
 
     if (host_addr == MAP_FAILED) {