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mm/vmalloc, mm/kasan: respect gfp mask in kasan_populate_vmalloc()

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kasan_populate_vmalloc() and its helpers ignore the caller's gfp_mask and
always allocate memory using the hardcoded GFP_KERNEL flag.  This makes
them inconsistent with vmalloc(), which was recently extended to support
GFP_NOFS and GFP_NOIO allocations.

Page table allocations performed during shadow population also ignore the
external gfp_mask.  To preserve the intended semantics of GFP_NOFS and
GFP_NOIO, wrap the apply_to_page_range() calls into the appropriate
memalloc scope.

xfs calls vmalloc with GFP_NOFS, so this bug could lead to deadlock.

There was a report here
https://lkml.kernel.org/r/686ea951.050a0220.385921.0016.GAE@google.com

This patch:
 - Extends kasan_populate_vmalloc() and helpers to take gfp_mask;
 - Passes gfp_mask down to alloc_pages_bulk() and __get_free_page();
 - Enforces GFP_NOFS/NOIO semantics with memalloc_*_save()/restore()
   around apply_to_page_range();
 - Updates vmalloc.c and percpu allocator call sites accordingly.

Link: https://lkml.kernel.org/r/20250831121058.92971-1-urezki@gmail.com
Fixes: 451769ebb7 ("mm/vmalloc: alloc GFP_NO{FS,IO} for vmalloc")
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reported-by: syzbot+3470c9ffee63e4abafeb@syzkaller.appspotmail.com
Reviewed-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Uladzislau Rezki (Sony)
2025-08-31 14:10:58 +02:00
committed by Andrew Morton
parent 04100f775c
commit 79357cd06d
3 changed files with 31 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/kasan.h
View File

@@ -562,7 +562,7 @@ static inline void kasan_init_hw_tags(void) { }
#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
void kasan_populate_early_vm_area_shadow(void *start, unsigned long size); void kasan_populate_early_vm_area_shadow(void *start, unsigned long size);
int kasan_populate_vmalloc(unsigned long addr, unsigned long size); int kasan_populate_vmalloc(unsigned long addr, unsigned long size, gfp_t gfp_mask);
void kasan_release_vmalloc(unsigned long start, unsigned long end, void kasan_release_vmalloc(unsigned long start, unsigned long end,
unsigned long free_region_start, unsigned long free_region_start,
unsigned long free_region_end, unsigned long free_region_end,
@@ -574,7 +574,7 @@ static inline void kasan_populate_early_vm_area_shadow(void *start,
unsigned long size) unsigned long size)
{ } { }
static inline int kasan_populate_vmalloc(unsigned long start, static inline int kasan_populate_vmalloc(unsigned long start,
unsigned long size) unsigned long size, gfp_t gfp_mask)
{ {
return 0; return 0;
} }
@@ -610,7 +610,7 @@ static __always_inline void kasan_poison_vmalloc(const void *start,
static inline void kasan_populate_early_vm_area_shadow(void *start, static inline void kasan_populate_early_vm_area_shadow(void *start,
unsigned long size) { } unsigned long size) { }
static inline int kasan_populate_vmalloc(unsigned long start, static inline int kasan_populate_vmalloc(unsigned long start,
unsigned long size) unsigned long size, gfp_t gfp_mask)
{ {
return 0; return 0;
} }

31
mm/kasan/shadow.c
View File

@@ -336,13 +336,13 @@ static void ___free_pages_bulk(struct page **pages, int nr_pages)
} }
} }
static int ___alloc_pages_bulk(struct page **pages, int nr_pages) static int ___alloc_pages_bulk(struct page **pages, int nr_pages, gfp_t gfp_mask)
{ {
unsigned long nr_populated, nr_total = nr_pages; unsigned long nr_populated, nr_total = nr_pages;
struct page **page_array = pages; struct page **page_array = pages;
while (nr_pages) { while (nr_pages) {
nr_populated = alloc_pages_bulk(GFP_KERNEL, nr_pages, pages); nr_populated = alloc_pages_bulk(gfp_mask, nr_pages, pages);
if (!nr_populated) { if (!nr_populated) {
___free_pages_bulk(page_array, nr_total - nr_pages); ___free_pages_bulk(page_array, nr_total - nr_pages);
return -ENOMEM; return -ENOMEM;
@@ -354,25 +354,42 @@ static int ___alloc_pages_bulk(struct page **pages, int nr_pages)
return 0; return 0;
} }
static int __kasan_populate_vmalloc(unsigned long start, unsigned long end) static int __kasan_populate_vmalloc(unsigned long start, unsigned long end, gfp_t gfp_mask)
{ {
unsigned long nr_pages, nr_total = PFN_UP(end - start); unsigned long nr_pages, nr_total = PFN_UP(end - start);
struct vmalloc_populate_data data; struct vmalloc_populate_data data;
unsigned int flags;
int ret = 0; int ret = 0;
data.pages = (struct page **)__get_free_page(GFP_KERNEL | __GFP_ZERO); data.pages = (struct page **)__get_free_page(gfp_mask | __GFP_ZERO);
if (!data.pages) if (!data.pages)
return -ENOMEM; return -ENOMEM;
while (nr_total) { while (nr_total) {
nr_pages = min(nr_total, PAGE_SIZE / sizeof(data.pages[0])); nr_pages = min(nr_total, PAGE_SIZE / sizeof(data.pages[0]));
ret = ___alloc_pages_bulk(data.pages, nr_pages); ret = ___alloc_pages_bulk(data.pages, nr_pages, gfp_mask);
if (ret) if (ret)
break; break;
data.start = start; data.start = start;
/*
* page tables allocations ignore external gfp mask, enforce it
* by the scope API
*/
if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
flags = memalloc_nofs_save();
else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
flags = memalloc_noio_save();
ret = apply_to_page_range(&init_mm, start, nr_pages * PAGE_SIZE, ret = apply_to_page_range(&init_mm, start, nr_pages * PAGE_SIZE,
kasan_populate_vmalloc_pte, &data); kasan_populate_vmalloc_pte, &data);
if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
memalloc_nofs_restore(flags);
else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
memalloc_noio_restore(flags);
___free_pages_bulk(data.pages, nr_pages); ___free_pages_bulk(data.pages, nr_pages);
if (ret) if (ret)
break; break;
@@ -386,7 +403,7 @@ static int __kasan_populate_vmalloc(unsigned long start, unsigned long end)
return ret; return ret;
} }
int kasan_populate_vmalloc(unsigned long addr, unsigned long size) int kasan_populate_vmalloc(unsigned long addr, unsigned long size, gfp_t gfp_mask)
{ {
unsigned long shadow_start, shadow_end; unsigned long shadow_start, shadow_end;
int ret; int ret;
@@ -415,7 +432,7 @@ int kasan_populate_vmalloc(unsigned long addr, unsigned long size)
shadow_start = PAGE_ALIGN_DOWN(shadow_start); shadow_start = PAGE_ALIGN_DOWN(shadow_start);
shadow_end = PAGE_ALIGN(shadow_end); shadow_end = PAGE_ALIGN(shadow_end);
ret = __kasan_populate_vmalloc(shadow_start, shadow_end); ret = __kasan_populate_vmalloc(shadow_start, shadow_end, gfp_mask);
if (ret) if (ret)
return ret; return ret;

8
mm/vmalloc.c
View File

@@ -2026,6 +2026,8 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
if (unlikely(!vmap_initialized)) if (unlikely(!vmap_initialized))
return ERR_PTR(-EBUSY); return ERR_PTR(-EBUSY);
/* Only reclaim behaviour flags are relevant. */
gfp_mask = gfp_mask & GFP_RECLAIM_MASK;
might_sleep(); might_sleep();
/* /*
@@ -2038,8 +2040,6 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
*/ */
va = node_alloc(size, align, vstart, vend, &addr, &vn_id); va = node_alloc(size, align, vstart, vend, &addr, &vn_id);
if (!va) { if (!va) {
gfp_mask = gfp_mask & GFP_RECLAIM_MASK;
va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node); va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node);
if (unlikely(!va)) if (unlikely(!va))
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
@@ -2089,7 +2089,7 @@ retry:
BUG_ON(va->va_start < vstart); BUG_ON(va->va_start < vstart);
BUG_ON(va->va_end > vend); BUG_ON(va->va_end > vend);
ret = kasan_populate_vmalloc(addr, size); ret = kasan_populate_vmalloc(addr, size, gfp_mask);
if (ret) { if (ret) {
free_vmap_area(va); free_vmap_area(va);
return ERR_PTR(ret); return ERR_PTR(ret);
@@ -4826,7 +4826,7 @@ retry:
/* populate the kasan shadow space */ /* populate the kasan shadow space */
for (area = 0; area < nr_vms; area++) { for (area = 0; area < nr_vms; area++) {
if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area])) if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area], GFP_KERNEL))
goto err_free_shadow; goto err_free_shadow;
} }