mirrors/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2025-11-04 10:40:15 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

mm/usercopy: Detect vmalloc overruns

Browse source 
If you have a vmalloc() allocation, or an address from calling vmap(),
you cannot overrun the vm_area which describes it, regardless of the
size of the underlying allocation.  This probably doesn't do much for
security because vmalloc comes with guard pages these days, but it
prevents usercopy aborts when copying to a vmap() of smaller pages.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220110231530.665970-3-willy@infradead.org
This commit is contained in:
Matthew Wilcox (Oracle) 2022-01-10 23:15:28 +00:00 committed by Kees Cook
parent 4e140f59d2
commit 0aef499f31
1 changed files with 16 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

16
mm/usercopy.c
View file

@ -17,6 +17,7 @@
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/thread_info.h>
#include <linux/vmalloc.h>
#include <linux/atomic.h>
#include <linux/jump_label.h>
#include <asm/sections.h>
@ -238,6 +239,21 @@ static inline void check_heap_object(const void *ptr, unsigned long n,
return;
}
if (is_vmalloc_addr(ptr)) {
struct vm_struct *area = find_vm_area(ptr);
unsigned long offset;
if (!area) {
usercopy_abort("vmalloc", "no area", to_user, 0, n);
return;
}
offset = ptr - area->addr;
if (offset + n > get_vm_area_size(area))
usercopy_abort("vmalloc", NULL, to_user, offset, n);
return;
}
folio = virt_to_folio(ptr);
if (folio_test_slab(folio)) {