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kasan: don't assume percpu shadow allocations will succeed 

syzkaller and the fault injector showed that I was wrong to assume that
we could ignore percpu shadow allocation failures.

Handle failures properly.  Merge all the allocated areas back into the
free list and release the shadow, then clean up and return NULL.  The
shadow is released unconditionally, which relies upon the fact that the
release function is able to tolerate pages not being present.

Also clean up shadows in the recovery path - currently they are not
released, which leaks a bit of memory.

Link: http://lkml.kernel.org/r/20191205140407.1874-3-dja@axtens.net
Fixes: 3c5c3cfb9e ("kasan: support backing vmalloc space with real shadow memory")
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reported-by: syzbot+82e323920b78d54aaed5@syzkaller.appspotmail.com
Reported-by: syzbot+59b7daa4315e07a994f1@syzkaller.appspotmail.com
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Daniel Axtens 2019-12-17 20:51:49 -08:00 committed by Linus Torvalds
parent e218f1ca39
commit 253a496d8e
1 changed files with 38 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
mm/vmalloc.c
View File

@ -3288,7 +3288,7 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
struct vmap_area **vas, *va;
struct vm_struct **vms;
int area, area2, last_area, term_area;
unsigned long base, start, size, end, last_end;
unsigned long base, start, size, end, last_end, orig_start, orig_end;
bool purged = false;
enum fit_type type;
@ -3418,6 +3418,15 @@ retry:
spin_unlock(&free_vmap_area_lock);
/* populate the kasan shadow space */
for (area = 0; area < nr_vms; area++) {
if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area]))
goto err_free_shadow;
kasan_unpoison_vmalloc((void *)vas[area]->va_start,
sizes[area]);
}
/* insert all vm's */
spin_lock(&vmap_area_lock);
for (area = 0; area < nr_vms; area++) {
@ -3428,13 +3437,6 @@ retry:
}
spin_unlock(&vmap_area_lock);
/* populate the shadow space outside of the lock */
for (area = 0; area < nr_vms; area++) {
/* assume success here */
kasan_populate_vmalloc(vas[area]->va_start, sizes[area]);
kasan_unpoison_vmalloc((void *)vms[area]->addr, sizes[area]);
}
kfree(vas);
return vms;
@ -3446,8 +3448,12 @@ recovery:
* and when pcpu_get_vm_areas() is success.
*/
while (area--) {
merge_or_add_vmap_area(vas[area], &free_vmap_area_root,
&free_vmap_area_list);
orig_start = vas[area]->va_start;
orig_end = vas[area]->va_end;
va = merge_or_add_vmap_area(vas[area], &free_vmap_area_root,
&free_vmap_area_list);
kasan_release_vmalloc(orig_start, orig_end,
va->va_start, va->va_end);
vas[area] = NULL;
}
@ -3482,6 +3488,28 @@ err_free2:
kfree(vas);
kfree(vms);
return NULL;
err_free_shadow:
spin_lock(&free_vmap_area_lock);
/*
* We release all the vmalloc shadows, even the ones for regions that
* hadn't been successfully added. This relies on kasan_release_vmalloc
* being able to tolerate this case.
*/
for (area = 0; area < nr_vms; area++) {
orig_start = vas[area]->va_start;
orig_end = vas[area]->va_end;
va = merge_or_add_vmap_area(vas[area], &free_vmap_area_root,
&free_vmap_area_list);
kasan_release_vmalloc(orig_start, orig_end,
va->va_start, va->va_end);
vas[area] = NULL;
kfree(vms[area]);
}
spin_unlock(&free_vmap_area_lock);
kfree(vas);
kfree(vms);
return NULL;
}
/**