Commit fa034538 authored by David Howells's avatar David Howells Committed by Greg Kroah-Hartman

afs: Fix the maths in afs_fs_store_data()


[ Upstream commit 146a1192 ]

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
loff_t.

Fix by casting the operands to loff_t.
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1efae6ca
......@@ -1225,7 +1225,7 @@ int afs_fs_store_data(struct afs_server *server, struct afs_writeback *wb,
_enter(",%x,{%x:%u},,",
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;
......
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