From: David Howells Date: Thu, 16 Mar 2017 16:27:47 +0000 (+0000) Subject: afs: Fix the maths in afs_fs_store_data() X-Git-Tag: v3.18.89~39 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=916426b19350c36e0a4a8a9b4e457e1099b9505e;p=thirdparty%2Fkernel%2Fstable.git afs: Fix the maths in afs_fs_store_data() [ 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 loff_t. Fix by casting the operands to loff_t. Signed-off-by: David Howells Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c index c2e930ec28889..4abafa196d66e 100644 --- a/fs/afs/fsclient.c +++ b/fs/afs/fsclient.c @@ -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;