From: Jiri Slaby <jslaby@xxxxxxx>
ext4_iomap_begin() has a bug where offset returned in the iomap
structure will be truncated to unsigned long size. On 64-bit
architectures this is fine but on 32-bit architectures obviously not.
Not many places actually use the offset stored in the iomap structure
but one of visible failures is in SEEK_HOLE / SEEK_DATA implementation.
If we create a file like:
dd if=/dev/urandom of=file bs=1k seek=8m count=1
then
lseek64("file", 0x100000000ULL, SEEK_DATA)
wrongly returns 0x100000000 on unfixed kernel while it should return
0x200000000. Avoid the overflow by proper type cast.
Fixes: 545052e9e35a ("ext4: Switch to iomap for SEEK_HOLE / SEEK_DATA")
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/ext4/inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c94780075b04..c07d6456b548 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3524,7 +3524,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
iomap->flags |= IOMAP_F_DIRTY;
iomap->bdev = inode->i_sb->s_bdev;
iomap->dax_dev = sbi->s_daxdev;
- iomap->offset = first_block << blkbits;
+ iomap->offset = (u64)first_block << blkbits;
iomap->length = (u64)map.m_len << blkbits;
if (ret == 0) {
--
2.13.6
