[Xen-devel,18/20] xen/arm: mm: Check start is always before end in {destroy, modify}_xen_mappings

Message ID 20190422164937.21350-19-julien.grall@arm.com
State Superseded
Headers show
Series
  • xen/arm: Clean-up & fixes in boot/mm code
Related show

Commit Message

Julien Grall April 22, 2019, 4:49 p.m.
The two helpers {destroy, modify}_xen_mappings don't check that the
start is always before the end. This should never happen but if it
happens, it will result to unexpected behavior.

Catch such issues earlier on by adding an ASSERT in destroy_xen_mappings
and modify_xen_mappings.

Signed-off-by: Julien Grall <julien.grall@arm.com>
---
 xen/arch/arm/mm.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Andrii Anisov May 3, 2019, 3:59 p.m. | #1
On 22.04.19 19:49, Julien Grall wrote:
> The two helpers {destroy, modify}_xen_mappings don't check that the
> start is always before the end. This should never happen but if it
> happens, it will result to unexpected behavior.
> 
> Catch such issues earlier on by adding an ASSERT in destroy_xen_mappings
> and modify_xen_mappings.
> 
> Signed-off-by: Julien Grall <julien.grall@arm.com>


Reviewed-by: Andrii Anisov <andrii_anisov@epam.com>

Patch

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index ee541a38e3..d6157c35d6 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -1072,11 +1072,13 @@  int populate_pt_range(unsigned long virt, unsigned long nr_mfns)
 
 int destroy_xen_mappings(unsigned long v, unsigned long e)
 {
+    ASSERT(v <= e);
     return create_xen_entries(REMOVE, v, INVALID_MFN, (e - v) >> PAGE_SHIFT, 0);
 }
 
 int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int flags)
 {
+    ASSERT(s <= e);
     return create_xen_entries(MODIFY, s, INVALID_MFN, (e - s) >> PAGE_SHIFT,
                               flags);
 }