[hurd] 18/31: libdiskfs: Reject LFS seeks and read/writes

[Samuel Thibault]

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sthibault pushed a commit to branch upstream
in repository hurd.

commit f2d22b3bab4de4b20c857bf6f0191fb6c000fd14
Author: Samuel Thibault <address@hidden>
Date:   Tue Apr 26 23:42:25 2016 +0200

    libdiskfs: Reject LFS seeks and read/writes
    
    vm_offset_t (used by pager_memcpy) is not 64bit-ready yet. Reject requests
    which go further than this.
    
    * libdiskfs/io-seek.c (diskfs_S_io_seek): Return EFBIG when requested offset
    is beyond limits of vm_offset_t.
    * libdiskfs/rdwr-internal.c (_diskfs_rdwr_internal): Return EFBIG when
    request goes beyond limits of vm_offset_t.
---
 libdiskfs/io-seek.c       | 8 ++++++++
 libdiskfs/rdwr-internal.c | 7 ++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/libdiskfs/io-seek.c b/libdiskfs/io-seek.c
index 9e3ff09..0018a71 100644
--- a/libdiskfs/io-seek.c
+++ b/libdiskfs/io-seek.c
@@ -46,6 +46,14 @@ diskfs_S_io_seek (struct protid *cred,
       offset += np->dn_stat.st_size;
     case SEEK_SET:
     check:
+      /* pager_memcpy inherently uses vm_offset_t, which may be smaller than
+         off_t.  */
+      if (sizeof(off_t) > sizeof(vm_offset_t) &&
+         offset > ((off_t) 1) << (sizeof(vm_offset_t) * 8))
+       {
+         err = EFBIG;
+         break;
+       }
       if (offset >= 0)
        {
          *newoffset = cred->po->filepointer = offset;
diff --git a/libdiskfs/rdwr-internal.c b/libdiskfs/rdwr-internal.c
index 18a4ae1..0d40551 100644
--- a/libdiskfs/rdwr-internal.c
+++ b/libdiskfs/rdwr-internal.c
@@ -58,7 +58,12 @@ _diskfs_rdwr_internal (struct node *np,
   if (memobj == MACH_PORT_NULL)
     return errno;
 
-  err = pager_memcpy (diskfs_get_filemap_pager_struct (np), memobj,
+  /* pager_memcpy inherently uses vm_offset_t, which may be smaller than 
off_t.  */
+  if (sizeof(off_t) > sizeof(vm_offset_t) &&
+      offset + *amt > ((off_t) 1) << (sizeof(vm_offset_t) * 8))
+    err = EFBIG;
+  else
+    err = pager_memcpy (diskfs_get_filemap_pager_struct (np), memobj,
                      offset, data, amt, prot);
 
   if (!diskfs_check_readonly () && !notime)

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