diff mbox series

[1/1] exfat: fix i_blocks for files truncated over 4 GiB

Message ID 20211118212828.4360-2-cvubrugier@fastmail.fm (mailing list archive)
State New, archived
Headers show
Series exfat: fix i_blocks for files truncated over 4 GiB | expand

Commit Message

Christophe Vu-Brugier Nov. 18, 2021, 9:28 p.m. UTC 
From: Christophe Vu-Brugier <christophe.vu-brugier@seagate.com>

In exfat_truncate(), the computation of inode->i_blocks is wrong if
the file is larger than 4 GiB because a 32-bit variable is used as a
mask. This is fixed by casting the variable to loff_t which is 64-bit.

Also fix the same computation in exfat_read_root().

This commit is similar to Sungjong Seo's fix in exfat_fill_inode()
last month:

  commit 0c336d6e33f4 ("exfat: fix incorrect loading of i_blocks for
                        large files")

Signed-off-by: Christophe Vu-Brugier <christophe.vu-brugier@seagate.com>
---
 fs/exfat/file.c  | 2 +-
 fs/exfat/super.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

Comments

Matthew Wilcox Nov. 18, 2021, 9:50 p.m. UTC | #1 
On Thu, Nov 18, 2021 at 10:28:28PM +0100, Christophe Vu-Brugier wrote:
>  	inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
> -			~(sbi->cluster_size - 1)) >> inode->i_blkbits;
> +		~((loff_t)sbi->cluster_size - 1)) >> inode->i_blkbits;

Isn't this a convoluted way to write:

	inode->i_blocks = round_up(i_size_read(inode), sbi->cluster_size) >>
				inode->i_blkbits;
?
Christophe Vu-Brugier Nov. 18, 2021, 10:43 p.m. UTC | #2 
Hi Matthew,

Le 18/11/2021 à 22:50, Matthew Wilcox a écrit :
> On Thu, Nov 18, 2021 at 10:28:28PM +0100, Christophe Vu-Brugier wrote:
>>   	inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
>> -			~(sbi->cluster_size - 1)) >> inode->i_blkbits;
>> +		~((loff_t)sbi->cluster_size - 1)) >> inode->i_blkbits;
> 
> Isn't this a convoluted way to write:
> 
> 	inode->i_blocks = round_up(i_size_read(inode), sbi->cluster_size) >>
> 				inode->i_blkbits;
> ?

Yes, it is. And we have evidence that it is more error prone.

I will update my patch with what you suggest.

Thanks!
diff mbox series

Patch

diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index 6af0191b648f..109ade79da33 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -252,7 +252,7 @@  void exfat_truncate(struct inode *inode, loff_t size)
 		mark_inode_dirty(inode);
 
 	inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
-			~(sbi->cluster_size - 1)) >> inode->i_blkbits;
+		~((loff_t)sbi->cluster_size - 1)) >> inode->i_blkbits;
 write_size:
 	aligned_size = i_size_read(inode);
 	if (aligned_size & (blocksize - 1)) {
diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index 5539ffc20d16..ea16769380c6 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -364,8 +364,8 @@  static int exfat_read_root(struct inode *inode)
 	inode->i_op = &exfat_dir_inode_operations;
 	inode->i_fop = &exfat_dir_operations;
 
-	inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1))
-			& ~(sbi->cluster_size - 1)) >> inode->i_blkbits;
+	inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
+		~((loff_t)sbi->cluster_size - 1)) >> inode->i_blkbits;
 	EXFAT_I(inode)->i_pos = ((loff_t)sbi->root_dir << 32) | 0xffffffff;
 	EXFAT_I(inode)->i_size_aligned = i_size_read(inode);
 	EXFAT_I(inode)->i_size_ondisk = i_size_read(inode);