[Xen-changelog] [xen stable-4.8] tools/oxenstored: Make evaluation order explicit

[patchbot@xxxxxxx]

commit 712082daee028b8c4fcdcbe72876aee58485dcf4
Author:     Christian Lindig <christian.lindig@xxxxxxxxxx>
AuthorDate: Mon Aug 13 17:26:56 2018 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Aug 14 17:27:26 2018 +0100

    tools/oxenstored: Make evaluation order explicit
    
    In Store.path_write(), Path.apply_modify() updates the node_created
    reference and both the value of apply_modify() and node_created are
    returned by path_write().
    
    At least with OCaml 4.06.1 this leads to the value of node_created being
    returned *before* it is updated by apply_modify().  This in turn leads
    to the quota for a domain not being updated in Store.write().  Hence, a
    guest can create an unlimited number of entries in xenstore.
    
    The fix is to make evaluation order explicit.
    
    This is XSA-272.
    
    Signed-off-by: Christian Lindig <christian.lindig@xxxxxxxxxx>
    Reviewed-by: Rob Hoes <rob.hoes@xxxxxxxxxx>
    (cherry picked from commit 73392c7fd14c59f8c96e0b2eeeb329e4ae9086b6)
---
 tools/ocaml/xenstored/store.ml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/ocaml/xenstored/store.ml b/tools/ocaml/xenstored/store.ml
index 9f619b8fd5..8b0727f8a8 100644
--- a/tools/ocaml/xenstored/store.ml
+++ b/tools/ocaml/xenstored/store.ml
@@ -257,7 +257,8 @@ let path_write store perm path value =
                Node.check_perm store.root perm Perms.WRITE;
                Node.set_value store.root value, false
        ) else
-               Path.apply_modify store.root path do_write, !node_created
+               let root = Path.apply_modify store.root path do_write in
+               root, !node_created
 
 let path_rm store perm path =
        let do_rm node name =
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.8

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