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Commit a33f13ef authored by Joel Becker's avatar Joel Becker
Browse files

libfs: Fix shift bug in generic_check_addressable() 



generic_check_addressable() erroneously shifts pages down by a block
factor when it should be shifting up.  To prevent overflow, we shift
blocks down to pages.

Signed-off-by: default avatarJoel Becker <joel.becker@oracle.com>
parent 3bdb8efd

fs/libfs.c

+4 −4
Original line number Diff line number Diff line
@@ -925,6 +925,8 @@ EXPORT_SYMBOL(generic_file_fsync); 
int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)

{

	u64 last_fs_block = num_blocks - 1;

	u64 last_fs_page =

		last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits);



	if (unlikely(num_blocks == 0))

		return 0;
@@ -932,10 +934,8 @@ int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) 
	if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT))

		return -EINVAL;



	if ((last_fs_block >

	     (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||

	    (last_fs_block >

	     (pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - blocksize_bits))) {

	if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||

	    (last_fs_page > (pgoff_t)(~0ULL))) {

		return -EFBIG;

	}

	return 0;