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-rw-r--r--mm/mmap.c32
1 files changed, 32 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 9d5968d1e8e3..6fc435760086 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1324,6 +1324,35 @@ static inline int mlock_future_check(struct mm_struct *mm,
return 0;
}
+static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
+{
+ if (S_ISREG(inode->i_mode))
+ return inode->i_sb->s_maxbytes;
+
+ if (S_ISBLK(inode->i_mode))
+ return MAX_LFS_FILESIZE;
+
+ /* Special "we do even unsigned file positions" case */
+ if (file->f_mode & FMODE_UNSIGNED_OFFSET)
+ return 0;
+
+ /* Yes, random drivers might want more. But I'm tired of buggy drivers */
+ return ULONG_MAX;
+}
+
+static inline bool file_mmap_ok(struct file *file, struct inode *inode,
+ unsigned long pgoff, unsigned long len)
+{
+ u64 maxsize = file_mmap_size_max(file, inode);
+
+ if (maxsize && len > maxsize)
+ return false;
+ maxsize -= len;
+ if (pgoff > maxsize >> PAGE_SHIFT)
+ return false;
+ return true;
+}
+
/*
* The caller must hold down_write(&current->mm->mmap_sem).
*/
@@ -1409,6 +1438,9 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
struct inode *inode = file_inode(file);
unsigned long flags_mask;
+ if (!file_mmap_ok(file, inode, pgoff, len))
+ return -EOVERFLOW;
+
flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
switch (flags & MAP_TYPE) {