[PATCH 3.18 30/69] afs: Fix the maths in afs_fs_store_data()
From: Greg Kroah-Hartman
Date: Mon Dec 18 2017 - 13:31:58 EST
3.18-stable review patch. If anyone has any objections, please let me know.
From: David Howells <dhowells@xxxxxxxxxx>
[ Upstream commit 146a1192783697810b63a1e41c4d59fc93387340 ]
afs_fs_store_data() works out of the size of the write it's going to make,
but it uses 32-bit unsigned subtraction in one place that gets
automatically cast to loff_t.
However, if to < offset, then the number goes negative, but as the result
isn't signed, this doesn't get sign-extended to 64-bits when placed in a
Fix by casting the operands to loff_t.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
fs/afs/fsclient.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
@@ -1225,7 +1225,7 @@ int afs_fs_store_data(struct afs_server
key_serial(wb->key), vnode->fid.vid, vnode->fid.vnode);
- size = to - offset;
+ size = (loff_t)to - (loff_t)offset;
if (first != last)
size += (loff_t)(last - first) << PAGE_SHIFT;
pos = (loff_t)first << PAGE_SHIFT;