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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, aryabinin@virtuozzo.com, cai@lca.pw,
	dja@axtens.net, dvyukov@google.com, glider@google.com,
	linux-mm@kvack.org, mm-commits@vger.kernel.org,
	torvalds@linux-foundation.org, urezki@gmail.com
Subject: [patch 3/6] kasan: use apply_to_existing_page_range() for releasing vmalloc shadow
Date: Tue, 17 Dec 2019 20:51:46 -0800	[thread overview]
Message-ID: <20191218045146.MXsRxaBsb%akpm@linux-foundation.org> (raw)
In-Reply-To: <20191217205020.6e2eaefc78710ec646e99aa9@linux-foundation.org>

From: Daniel Axtens <dja@axtens.net>
Subject: kasan: use apply_to_existing_page_range() for releasing vmalloc shadow

kasan_release_vmalloc uses apply_to_page_range to release vmalloc shadow. 
Unfortunately, apply_to_page_range can allocate memory to fill in page
table entries, which is not what we want.

Also, kasan_release_vmalloc is called under free_vmap_area_lock, so if
apply_to_page_range does allocate memory, we get a sleep in atomic bug:

	BUG: sleeping function called from invalid context at mm/page_alloc.c:46=
81
	in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 15087, name:

	Call Trace:
	 __dump_stack lib/dump_stack.c:77 [inline]
	 dump_stack+0x199/0x216 lib/dump_stack.c:118
	 ___might_sleep.cold.97+0x1f5/0x238 kernel/sched/core.c:6800
	 __might_sleep+0x95/0x190 kernel/sched/core.c:6753
	 prepare_alloc_pages mm/page_alloc.c:4681 [inline]
	 __alloc_pages_nodemask+0x3cd/0x890 mm/page_alloc.c:4730
	 alloc_pages_current+0x10c/0x210 mm/mempolicy.c:2211
	 alloc_pages include/linux/gfp.h:532 [inline]
	 __get_free_pages+0xc/0x40 mm/page_alloc.c:4786
	 __pte_alloc_one_kernel include/asm-generic/pgalloc.h:21 [inline]
	 pte_alloc_one_kernel include/asm-generic/pgalloc.h:33 [inline]
	 __pte_alloc_kernel+0x1d/0x200 mm/memory.c:459
	 apply_to_pte_range mm/memory.c:2031 [inline]
	 apply_to_pmd_range mm/memory.c:2068 [inline]
	 apply_to_pud_range mm/memory.c:2088 [inline]
	 apply_to_p4d_range mm/memory.c:2108 [inline]
	 apply_to_page_range+0x77d/0xa00 mm/memory.c:2133
	 kasan_release_vmalloc+0xa7/0xc0 mm/kasan/common.c:970
	 __purge_vmap_area_lazy+0xcbb/0x1f30 mm/vmalloc.c:1313
	 try_purge_vmap_area_lazy mm/vmalloc.c:1332 [inline]
	 free_vmap_area_noflush+0x2ca/0x390 mm/vmalloc.c:1368
	 free_unmap_vmap_area mm/vmalloc.c:1381 [inline]
	 remove_vm_area+0x1cc/0x230 mm/vmalloc.c:2209
	 vm_remove_mappings mm/vmalloc.c:2236 [inline]
	 __vunmap+0x223/0xa20 mm/vmalloc.c:2299
	 __vfree+0x3f/0xd0 mm/vmalloc.c:2356
	 __vmalloc_area_node mm/vmalloc.c:2507 [inline]
	 __vmalloc_node_range+0x5d5/0x810 mm/vmalloc.c:2547
	 __vmalloc_node mm/vmalloc.c:2607 [inline]
	 __vmalloc_node_flags mm/vmalloc.c:2621 [inline]
	 vzalloc+0x6f/0x80 mm/vmalloc.c:2666
	 alloc_one_pg_vec_page net/packet/af_packet.c:4233 [inline]
	 alloc_pg_vec net/packet/af_packet.c:4258 [inline]
	 packet_set_ring+0xbc0/0x1b50 net/packet/af_packet.c:4342
	 packet_setsockopt+0xed7/0x2d90 net/packet/af_packet.c:3695
	 __sys_setsockopt+0x29b/0x4d0 net/socket.c:2117
	 __do_sys_setsockopt net/socket.c:2133 [inline]
	 __se_sys_setsockopt net/socket.c:2130 [inline]
	 __x64_sys_setsockopt+0xbe/0x150 net/socket.c:2130
	 do_syscall_64+0xfa/0x780 arch/x86/entry/common.c:294
	 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Switch to using the apply_to_existing_page_range() helper instead, which
won't allocate memory.

[akpm@linux-foundation.org: s/apply_to_existing_pages/apply_to_existing_page_range/]
Link: http://lkml.kernel.org/r/20191205140407.1874-2-dja@axtens.net
Fixes: 3c5c3cfb9ef4 ("kasan: support backing vmalloc space with real shad=
ow memory")
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.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>
---

 mm/kasan/common.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/mm/kasan/common.c~kasan-use-apply_to_existing_pages-for-releasing-vmalloc-shadow
+++ a/mm/kasan/common.c
@@ -957,6 +957,7 @@ void kasan_release_vmalloc(unsigned long
 {
 	void *shadow_start, *shadow_end;
 	unsigned long region_start, region_end;
+	unsigned long size;
 
 	region_start = ALIGN(start, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE);
 	region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE);
@@ -979,9 +980,11 @@ void kasan_release_vmalloc(unsigned long
 	shadow_end = kasan_mem_to_shadow((void *)region_end);
 
 	if (shadow_end > shadow_start) {
-		apply_to_page_range(&init_mm, (unsigned long)shadow_start,
-				    (unsigned long)(shadow_end - shadow_start),
-				    kasan_depopulate_vmalloc_pte, NULL);
+		size = shadow_end - shadow_start;
+		apply_to_existing_page_range(&init_mm,
+					     (unsigned long)shadow_start,
+					     size, kasan_depopulate_vmalloc_pte,
+					     NULL);
 		flush_tlb_kernel_range((unsigned long)shadow_start,
 				       (unsigned long)shadow_end);
 	}
_


  parent reply	other threads:[~2019-12-18  4:51 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-18  4:50 incoming Andrew Morton
2019-12-18  4:51 ` [patch 1/6] kasan: fix crashes on access to memory mapped by vm_map_ram() Andrew Morton
2019-12-18  4:51 ` [patch 2/6] mm/memory.c: add apply_to_existing_page_range() helper Andrew Morton
2019-12-18  4:51 ` Andrew Morton [this message]
2019-12-18  4:51 ` [patch 4/6] kasan: don't assume percpu shadow allocations will succeed Andrew Morton
2019-12-18  4:51 ` [patch 5/6] mm: vmscan: protect shrinker idr replace with CONFIG_MEMCG Andrew Morton
2019-12-18  4:51 ` [patch 6/6] lib/Kconfig.debug: fix some messed up configurations Andrew Morton

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