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Message-Id: <20200425091338.24283-1-changbin.du@gmail.com>
Date: Sat, 25 Apr 2020 17:13:38 +0800
From: Changbin Du <changbin.du@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>,
David Rientjes <rientjes@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Kees Cook <keescook@...omium.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, Changbin Du <changbin.du@...il.com>
Subject: [PATCH] mm/slub: do not place freelist pointer to middle of object if redzone is on
The recent kernel fails to boot when slub redzone is turned on. This is
caused by commit 3202fa62fb ("slub: relocate freelist pointer to middle of
object") which relocates freelist pointer to middle of object. In this
case, get_track() gets a wrong address and then the redzone is overwritten.
This patch fixes it by relocating freelist pointer after the object, as
what slub posion does.
[ 2.390256][ T0] =============================================================================
[ 2.392816][ T0] BUG kmem_cache_node (Not tainted): Redzone overwritten
[ 2.393735][ T0] -----------------------------------------------------------------------------
[ 2.393735][ T0]
[ 2.395168][ T0] Disabling lock debugging due to kernel taint
[ 2.395923][ T0] INFO: 0xffff88805c000380-0xffff88805c000387 @offset=896. First byte 0x0 instead of 0xbb
[ 2.397175][ T0] INFO: Slab 0xffffea0001700000 objects=25 used=25 fp=0x0000000000000000 flags=0xfffffc0010200
[ 2.398882][ T0] INFO: Object 0xffff88805c000300 @offset=768 fp=0xffff88805c000580
[ 2.398882][ T0]
[ 2.400145][ T0] Redzone ffff88805c000280: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................
[ 2.401593][ T0] Redzone ffff88805c000290: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................
[ 2.403825][ T0] Redzone ffff88805c0002a0: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................
[ 2.405853][ T0] Redzone ffff88805c0002b0: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................
[ 2.407714][ T0] Redzone ffff88805c0002c0: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................
[ 2.411066][ T0] Redzone ffff88805c0002d0: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................
[ 2.413818][ T0] Redzone ffff88805c0002e0: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................
[ 2.415482][ T0] Redzone ffff88805c0002f0: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................
[ 2.416975][ T0] Object ffff88805c000300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.418445][ T0] Object ffff88805c000310: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.420183][ T0] Object ffff88805c000320: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.421911][ T0] Object ffff88805c000330: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.423491][ T0] Object ffff88805c000340: 00 00 00 00 00 00 00 00 e8 ed 4a b9 09 7b 20 83 ..........J..{ .
[ 2.425186][ T0] Object ffff88805c000350: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.426901][ T0] Object ffff88805c000360: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.428673][ T0] Object ffff88805c000370: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.430431][ T0] Redzone ffff88805c000380: 00 00 00 00 00 00 00 00 ........
[ 2.485141][ T0] Padding ffff88805c000490: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.494198][ T0] Padding ffff88805c0004a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.503094][ T0] Padding ffff88805c0004b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.578370][ T0] Padding ffff88805c0004c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.584420][ T0] Padding ffff88805c0004d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.590139][ T0] Padding ffff88805c0004e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.596915][ T0] Padding ffff88805c0004f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 2.604002][ T0] CPU: 0 PID: 0 Comm: swapper Tainted: G B 5.7.0-rc1+ #53
[ 2.608493][ T0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 2.612959][ T0] Call Trace:
[ 2.613953][ T0] dump_stack+0x8c/0xc0
[ 2.615063][ T0] check_bytes_and_report.cold+0x60/0x95
[ 2.616572][ T0] check_object+0x1c1/0x280
[ 2.617462][ T0] ? pvclock_clocksource_read+0xf6/0x1c0
[ 2.618646][ T0] ? __kmem_cache_create+0x16a/0x670
[ 2.619692][ T0] alloc_debug_processing+0x129/0x170
[ 2.620766][ T0] ___slab_alloc+0x58c/0x630
[ 2.621804][ T0] ? __kmem_cache_create+0x16a/0x670
[ 2.622631][ T0] ? print_unlock_imbalance_bug+0x40/0x40
[ 2.623630][ T0] ? lock_acquire+0x11f/0x200
[ 2.624421][ T0] ? __kmem_cache_create+0x16a/0x670
[ 2.625342][ T0] ? __slab_alloc+0x1c/0x30
[ 2.626106][ T0] ? ___slab_alloc+0x5/0x630
[ 2.626890][ T0] __slab_alloc+0x1c/0x30
[ 2.627500][ T0] kmem_cache_alloc_node+0xab/0x2e0
[ 2.628222][ T0] __kmem_cache_create+0x16a/0x670
[ 2.628883][ T0] ? mem_init_print_info+0x2af/0x2be
[ 2.629596][ T0] create_boot_cache+0xa4/0xc8
[ 2.630282][ T0] kmem_cache_init+0x80/0x14a
[ 2.631233][ T0] start_kernel+0x67a/0xa2a
[ 2.631905][ T0] ? thread_stack_cache_init+0x6/0x6
[ 2.632553][ T0] ? x86_family+0x5/0x20
[ 2.633085][ T0] ? load_ucode_bsp+0x50/0x216
[ 2.633629][ T0] secondary_startup_64+0xa4/0xb0
[ 2.634243][ T0] FIX kmem_cache_node: Restoring 0xffff88805c000380-0xffff88805c000387=0xbb
[ 2.634243][ T0]
[ 2.635532][ T0] FIX kmem_cache_node: Marking all objects used
[ 2.636287][ T0] =============================================================================
Fixes: 3202fa62fb ("slub: relocate freelist pointer to middle of object")
Cc: Kees Cook <keescook@...omium.org>
Signed-off-by: Changbin Du <changbin.du@...il.com>
---
mm/slub.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/slub.c b/mm/slub.c
index 332d4b459a90..59c5b49038b0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3570,7 +3570,7 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
*/
s->inuse = size;
- if (((flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)) ||
+ if (((flags & (SLAB_TYPESAFE_BY_RCU | SLAB_RED_ZONE | SLAB_POISON)) ||
s->ctor)) {
/*
* Relocate free pointer after the object if it is not
--
2.25.1
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