From: Ming Lei ming.lei@redhat.com
[ Upstream commit 153fcd5f6d93b8e1e4040b1337f564a10f8d93af ]
brd_free() may be called in failure path on one brd instance which disk isn't added yet, so release handler of gendisk may free the associated request_queue early and causes the following use-after-free[1].
This patch fixes this issue by associating gendisk with request_queue just before adding disk.
[1] KASAN: use-after-free Read in del_timer_syncNon-volatile memory driver v1.3 Linux agpgart interface v0.103 [drm] Initialized vgem 1.0.0 20120112 for virtual device on minor 0 usbcore: registered new interface driver udl ================================================================== BUG: KASAN: use-after-free in __lock_acquire+0x36d9/0x4c20 kernel/locking/lockdep.c:3218 Read of size 8 at addr ffff8801d1b6b540 by task swapper/0/1
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.0+ #88 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x244/0x39d lib/dump_stack.c:113 print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 __lock_acquire+0x36d9/0x4c20 kernel/locking/lockdep.c:3218 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 del_timer_sync+0xb7/0x270 kernel/time/timer.c:1283 blk_cleanup_queue+0x413/0x710 block/blk-core.c:809 brd_free+0x5d/0x71 drivers/block/brd.c:422 brd_init+0x2eb/0x393 drivers/block/brd.c:518 do_one_initcall+0x145/0x957 init/main.c:890 do_initcall_level init/main.c:958 [inline] do_initcalls init/main.c:966 [inline] do_basic_setup init/main.c:984 [inline] kernel_init_freeable+0x5c6/0x6b9 init/main.c:1148 kernel_init+0x11/0x1ae init/main.c:1068 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:350
Reported-by: syzbot+3701447012fe951dabb2@syzkaller.appspotmail.com Signed-off-by: Ming Lei ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/block/brd.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c index bb976598ee43..739f8dfd6fd7 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -396,15 +396,14 @@ static struct brd_device *brd_alloc(int i) disk->first_minor = i * max_part; disk->fops = &brd_fops; disk->private_data = brd; - disk->queue = brd->brd_queue; disk->flags = GENHD_FL_EXT_DEVT; sprintf(disk->disk_name, "ram%d", i); set_capacity(disk, rd_size * 2); - disk->queue->backing_dev_info->capabilities |= BDI_CAP_SYNCHRONOUS_IO; + brd->brd_queue->backing_dev_info->capabilities |= BDI_CAP_SYNCHRONOUS_IO;
/* Tell the block layer that this is not a rotational device */ - blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue); - blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, disk->queue); + blk_queue_flag_set(QUEUE_FLAG_NONROT, brd->brd_queue); + blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, brd->brd_queue);
return brd;
@@ -436,6 +435,7 @@ static struct brd_device *brd_init_one(int i, bool *new)
brd = brd_alloc(i); if (brd) { + brd->brd_disk->queue = brd->brd_queue; add_disk(brd->brd_disk); list_add_tail(&brd->brd_list, &brd_devices); } @@ -503,8 +503,14 @@ static int __init brd_init(void)
/* point of no return */
- list_for_each_entry(brd, &brd_devices, brd_list) + list_for_each_entry(brd, &brd_devices, brd_list) { + /* + * associate with queue just before adding disk for + * avoiding to mess up failure path + */ + brd->brd_disk->queue = brd->brd_queue; add_disk(brd->brd_disk); + }
blk_register_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS, THIS_MODULE, brd_probe, NULL, NULL);