From d48df033095afadd82435e591ce66433bc6d3be2 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 9 Jun 2017 13:54:27 +0200 Subject: [PATCH] x86/32on64: properly honor add-to-physmap-batch's size MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit 407a3c00ff ("compat/memory: fix build with old gcc") "fixed" a build issue by switching to the use of uninitialized data. Due to - the bounding of the uninitialized data item - the accessed area being outside of Xen space - arguments being properly verified by the native hypercall function this is not a security issue. Reported-by: Marek Marczykowski-Górecki Signed-off-by: Jan Beulich Reviewed-by: Wei Liu Reviewed-by: Andrew Cooper master commit: 144aec4140515c53bb1676df71a469f3e285c557 master date: 2017-04-26 09:48:45 +0200 --- xen/common/compat/memory.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/xen/common/compat/memory.c b/xen/common/compat/memory.c index a31fa9b4d0..8e257a0a59 100644 --- a/xen/common/compat/memory.c +++ b/xen/common/compat/memory.c @@ -249,12 +249,14 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat) unsigned int limit = (COMPAT_ARG_XLAT_SIZE - sizeof(*nat.atpb)) / (sizeof(nat.atpb->idxs.p) + sizeof(nat.atpb->gpfns.p)); /* Use an intermediate variable to suppress warnings on old gcc: */ - unsigned int size = cmp.atpb.size; + unsigned int size; xen_ulong_t *idxs = (void *)(nat.atpb + 1); xen_pfn_t *gpfns = (void *)(idxs + limit); - if ( copy_from_guest(&cmp.atpb, compat, 1) || - !compat_handle_okay(cmp.atpb.idxs, size) || + if ( copy_from_guest(&cmp.atpb, compat, 1) ) + return -EFAULT; + size = cmp.atpb.size; + if ( !compat_handle_okay(cmp.atpb.idxs, size) || !compat_handle_okay(cmp.atpb.gpfns, size) || !compat_handle_okay(cmp.atpb.errs, size) ) return -EFAULT;