diff options
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 680506faceae..924839fac0e6 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1387,9 +1387,24 @@ unsigned long do_mmap(struct file *file, unsigned long addr, if (file) { struct inode *inode = file_inode(file); + unsigned long flags_mask; + + flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags; switch (flags & MAP_TYPE) { case MAP_SHARED: + /* + * Force use of MAP_SHARED_VALIDATE with non-legacy + * flags. E.g. MAP_SYNC is dangerous to use with + * MAP_SHARED as you don't know which consistency model + * you will get. We silently ignore unsupported flags + * with MAP_SHARED to preserve backward compatibility. + */ + flags &= LEGACY_MAP_MASK; + /* fall through */ + case MAP_SHARED_VALIDATE: + if (flags & ~flags_mask) + return -EOPNOTSUPP; if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) return -EACCES; |