[PATCH] uml: fix fault handler on write
The UML fault handler was recently changed to enforce PROT_NONE protections,
by requiring VM_READ or VM_EXEC on VMA's.
However, by mistake, things were changed such that VM_READ is always checked,
also on write faults; so a VMA mapped with only PROT_WRITE is not readable
(unless it's prefaulted with MAP_POPULATE or with a write), which is different
from i386.
Discovered while testing remap_file_pages protection support.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/um/kernel/trap_kern.c b/arch/um/kernel/trap_kern.c
index b5fc89f..d20361d 100644
--- a/arch/um/kernel/trap_kern.c
+++ b/arch/um/kernel/trap_kern.c
@@ -57,7 +57,8 @@
if(is_write && !(vma->vm_flags & VM_WRITE))
goto out;
- if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
+ /* Don't require VM_READ|VM_EXEC for write faults! */
+ if(!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
goto out;
do {
