[RFC,v3,22/28] linux-user: Replace g_memdup() by g_memdup2()

Commit Message

Philippe Mathieu-Daudé Sept. 3, 2021, 5:45 p.m. UTC

Per https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2-now/5538

  The old API took the size of the memory to duplicate as a guint,
  whereas most memory functions take memory sizes as a gsize. This
  made it easy to accidentally pass a gsize to g_memdup(). For large
  values, that would lead to a silent truncation of the size from 64
  to 32 bits, and result in a heap area being returned which is
  significantly smaller than what the caller expects. This can likely
  be exploited in various modules to cause a heap buffer overflow.

Replace g_memdup() by the safer g_memdup2() wrapper.

Signed-off-by: Philippe Mathieu-Daudé <[e-mail]>
---
do_open_by_handle_at() doesn't check:

    size + sizeof(struct file_handle) < 4GiB
---
 linux-user/syscall.c | 2 +-
 linux-user/uaccess.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Patch

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index ccd3892b2df..d3701007cb3 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7665,7 +7665,7 @@  static abi_long do_open_by_handle_at(abi_long mount_fd, abi_long handle,
         return -TARGET_EFAULT;
     }
 
-    fh = g_memdup(target_fh, total_size);
+    fh = g_memdup2(target_fh, total_size);
     fh->handle_bytes = size;
     fh->handle_type = tswap32(target_fh->handle_type);
 
diff --git a/linux-user/uaccess.c b/linux-user/uaccess.c
index 6a5b029607c..49eddbf4a4d 100644
--- a/linux-user/uaccess.c
+++ b/linux-user/uaccess.c
@@ -15,7 +15,7 @@  void *lock_user(int type, abi_ulong guest_addr, ssize_t len, bool copy)
     host_addr = g2h_untagged(guest_addr);
 #ifdef DEBUG_REMAP
     if (copy) {
-        host_addr = g_memdup(host_addr, len);
+        host_addr = g_memdup2(host_addr, len);
     } else {
         host_addr = g_malloc0(len);
     }