The size of block-device is larger than 16TB, and the os is 32bit.
If the offset of read/write is larger then 16TB. The index of address_space will
overflow and supply data from low offset instead.
when read-operation, in function do_generic_file_read():
>index = *ppos >> PAGE_CACHE_SHIFT;
Because the *ppos is larger than 16TB and the index is the type pgoff_t which 32bit
in 32bit-OS. So index will overflow.
When write-operation, in function generic_write_checks():
>if (likely(!isblk)) {
> .....
> } else {
>#ifdef CONFIG_BLOCK
> loff_t isize;
> if (bdev_read_only(I_BDEV(inode)))
return -EPERM;
> isize = i_size_read(inode);
> if (*pos >= isize) {
> if (*count || *pos > isize)
> return -ENOSPC;
> }
>
> if (*pos + *count > isize)
> *count = isize - *pos;
The code only check size.But continue code:
generic_file_buffered_write-->generic_perform_write-->blkdev_write_begin
--->block_write_begin()
> pgoff_t index = pos >> PAGE_CACHE_SHIFT;
The index will overflow again.
Although filesystem has a attribute s_maxbytes, the block-device was not create so no affect.
Signed-off-by: majianpeng <majianpeng@xxxxxxxxx>
---
fs/block_dev.c | 4 +++-
mm/filemap.c | 28 ++++++++++++++++++++++++++++
2 files changed, 31 insertions(+), 1 deletion(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index c2bbe1f..1752c0e 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -382,7 +382,9 @@ static loff_t block_llseek(struct file *file, loff_t offset, int origin)
mutex_lock(&bd_inode->i_mutex);
size = i_size_read(bd_inode);
-
+#if BITS_PER_LONG == 32
+ size = min_t(loff_t, size, (loff_t)0xFFFFFFFF * PAGE_CACHE_SIZE - 1);
+#endif
retval = -EINVAL;
switch (origin) {
case SEEK_END:
diff --git a/mm/filemap.c b/mm/filemap.c
index 79c4b2b..34a15bf 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1373,6 +1373,25 @@ int generic_segment_checks(const struct iovec *iov,
}
EXPORT_SYMBOL(generic_segment_checks);
+static inline
+int generic_read_block_checks(struct file *file, loff_t *pos, size_t *count)
+{
+ struct inode *inode = file->f_mapping->host;
+ loff_t isize = 0;
+#if BITS_PER_LONG == 32 && defined(CONFIG_BLOCK)
+ isize = min_t(loff_t, i_size_read(inode),
+ (loff_t)0xFFFFFFFF * PAGE_CACHE_SIZE - 1);
+ if (*pos >= isize) {
+ if (*count || *pos > isize)
+ return -ENOSPC;
+ }
+
+ if (*pos + *count > isize)
+ *count = isize - *pos;
+#endif
+ return 0;
+}
+
/**
* generic_file_aio_read - generic filesystem read routine
* @iocb: kernel I/O control block
@@ -1398,6 +1417,11 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
if (retval)
return retval;
+ if (S_ISBLK(filp->f_mapping->host->i_mode)) {
+ retval = generic_read_block_checks(filp, &pos, &count);
+ if (retval)
+ return retval;
+ }
/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
if (filp->f_flags & O_DIRECT) {
loff_t size;
@@ -2214,6 +2238,10 @@ inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, i
if (bdev_read_only(I_BDEV(inode)))
return -EPERM;
isize = i_size_read(inode);
+#if BITS_PER_LONG == 32
+ isize = min_t(loff_t, isize,
+ (loff_t)0xFFFFFFFF * PAGE_CACHE_SIZE - 1);
+#endif
if (*pos >= isize) {
if (*count || *pos > isize)
return -ENOSPC;
--
1.7.9.5
--------------
majianpeng
2012-05-29
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