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mm: kmsan: handle alloc failures in kmsan_vmap_pages_range_noflush() 

commit 47ebd0310e upstream.

As reported by Dipanjan Das, when KMSAN is used together with kernel fault
injection (or, generally, even without the latter), calls to kcalloc() or
__vmap_pages_range_noflush() may fail, leaving the metadata mappings for
the virtual mapping in an inconsistent state.  When these metadata
mappings are accessed later, the kernel crashes.

To address the problem, we return a non-zero error code from
kmsan_vmap_pages_range_noflush() in the case of any allocation/mapping
failure inside it, and make vmap_pages_range_noflush() return an error if
KMSAN fails to allocate the metadata.

This patch also removes KMSAN_WARN_ON() from vmap_pages_range_noflush(),
as these allocation failures are not fatal anymore.

Link: https://lkml.kernel.org/r/20230413131223.4135168-1-glider@google.com
Fixes: b073d7f8ae ("mm: kmsan: maintain KMSAN metadata for page operations")
Signed-off-by: Alexander Potapenko <glider@google.com>
Reported-by: Dipanjan Das <mail.dipanjan.das@gmail.com>
  Link: https://lore.kernel.org/linux-mm/CANX2M5ZRrRA64k0hOif02TjmY9kbbO2aCBPyq79es34RXZ=cAw@mail.gmail.com/
Reviewed-by: Marco Elver <elver@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexander Potapenko 2023-04-13 15:12:20 +02:00 committed by Greg Kroah-Hartman
parent 433a7ecaed
commit bd6f3421a5
3 changed files with 34 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
include/linux/kmsan.h
View File

@ -134,11 +134,12 @@ void kmsan_kfree_large(const void *ptr);
* @page_shift: page_shift passed to vmap_range_noflush().
*
* KMSAN maps shadow and origin pages of @pages into contiguous ranges in
* vmalloc metadata address range.
* vmalloc metadata address range. Returns 0 on success, callers must check
* for non-zero return value.
*/
void kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
pgprot_t prot, struct page **pages,
unsigned int page_shift);
int kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
pgprot_t prot, struct page **pages,
unsigned int page_shift);
/**
* kmsan_vunmap_kernel_range_noflush() - Notify KMSAN about a vunmap.
@ -282,12 +283,13 @@ static inline void kmsan_kfree_large(const void *ptr)
{
}
static inline void kmsan_vmap_pages_range_noflush(unsigned long start,
unsigned long end,
pgprot_t prot,
struct page **pages,
unsigned int page_shift)
static inline int kmsan_vmap_pages_range_noflush(unsigned long start,
unsigned long end,
pgprot_t prot,
struct page **pages,
unsigned int page_shift)
{
return 0;
}
static inline void kmsan_vunmap_range_noflush(unsigned long start,

27
mm/kmsan/shadow.c
View File

@ -216,27 +216,29 @@ void kmsan_free_page(struct page *page, unsigned int order)
kmsan_leave_runtime();
}
void kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
pgprot_t prot, struct page **pages,
unsigned int page_shift)
int kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
pgprot_t prot, struct page **pages,
unsigned int page_shift)
{
unsigned long shadow_start, origin_start, shadow_end, origin_end;
struct page **s_pages, **o_pages;
int nr, mapped;
int nr, mapped, err = 0;
if (!kmsan_enabled)
return;
return 0;
shadow_start = vmalloc_meta((void *)start, KMSAN_META_SHADOW);
shadow_end = vmalloc_meta((void *)end, KMSAN_META_SHADOW);
if (!shadow_start)
return;
return 0;
nr = (end - start) / PAGE_SIZE;
s_pages = kcalloc(nr, sizeof(*s_pages), GFP_KERNEL);
o_pages = kcalloc(nr, sizeof(*o_pages), GFP_KERNEL);
if (!s_pages || !o_pages)
if (!s_pages || !o_pages) {
err = -ENOMEM;
goto ret;
}
for (int i = 0; i < nr; i++) {
s_pages[i] = shadow_page_for(pages[i]);
o_pages[i] = origin_page_for(pages[i]);
@ -249,10 +251,16 @@ void kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
kmsan_enter_runtime();
mapped = __vmap_pages_range_noflush(shadow_start, shadow_end, prot,
s_pages, page_shift);
KMSAN_WARN_ON(mapped);
if (mapped) {
err = mapped;
goto ret;
}
mapped = __vmap_pages_range_noflush(origin_start, origin_end, prot,
o_pages, page_shift);
KMSAN_WARN_ON(mapped);
if (mapped) {
err = mapped;
goto ret;
}
kmsan_leave_runtime();
flush_tlb_kernel_range(shadow_start, shadow_end);
flush_tlb_kernel_range(origin_start, origin_end);
@ -262,6 +270,7 @@ void kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
ret:
kfree(s_pages);
kfree(o_pages);
return err;
}
/* Allocate metadata for pages allocated at boot time. */

6
mm/vmalloc.c
View File

@ -613,7 +613,11 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end,
int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
pgprot_t prot, struct page **pages, unsigned int page_shift)
{
kmsan_vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
int ret = kmsan_vmap_pages_range_noflush(addr, end, prot, pages,
page_shift);
if (ret)
return ret;
return __vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
}