From: ZhaoLong Wang wangzhaolong1@huawei.com

mainline inclusion from mainline-v6.7-rc1 commit d07cec9c238ae8fc6c1a9f3f5d30a2f8ec6cdc71 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8P68G

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

The following BUG is reported when a ubiblock is removed:

================================================================== BUG: KASAN: slab-use-after-free in ubiblock_cleanup+0x88/0xa0 [ubi] Read of size 4 at addr ffff88810c8f3804 by task ubiblock/1716

CPU: 5 PID: 1716 Comm: ubiblock Not tainted 6.6.0-rc2+ #135 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x37/0x50 print_report+0xd0/0x620 kasan_report+0xb6/0xf0 ubiblock_cleanup+0x88/0xa0 [ubi] ubiblock_remove+0x121/0x190 [ubi] vol_cdev_ioctl+0x355/0x630 [ubi] __x64_sys_ioctl+0xc7/0x100 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 RIP: 0033:0x7f08d7445577 Code: b3 66 90 48 8b 05 11 89 2c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e1 8 RSP: 002b:00007ffde05a3018 EFLAGS: 00000206 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007f08d7445577 RDX: 0000000000000000 RSI: 0000000000004f08 RDI: 0000000000000003 RBP: 0000000000816010 R08: 00000000008163a7 R09: 0000000000000000 R10: 0000000000000003 R11: 0000000000000206 R12: 0000000000000003 R13: 00007ffde05a3130 R14: 0000000000000000 R15: 0000000000000000 </TASK>

Allocated by task 1715: kasan_save_stack+0x22/0x50 kasan_set_track+0x25/0x30 __kasan_kmalloc+0x7f/0x90 __alloc_disk_node+0x40/0x2b0 __blk_mq_alloc_disk+0x3e/0xb0 ubiblock_create+0x2ba/0x620 [ubi] vol_cdev_ioctl+0x581/0x630 [ubi] __x64_sys_ioctl+0xc7/0x100 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Freed by task 0: kasan_save_stack+0x22/0x50 kasan_set_track+0x25/0x30 kasan_save_free_info+0x2b/0x50 __kasan_slab_free+0x10e/0x190 __kmem_cache_free+0x96/0x220 bdev_free_inode+0xa4/0xf0 rcu_core+0x496/0xec0 __do_softirq+0xeb/0x384

The buggy address belongs to the object at ffff88810c8f3800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 4 bytes inside of freed 1024-byte region [ffff88810c8f3800, ffff88810c8f3c00)

The buggy address belongs to the physical page: page:00000000d03de848 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10c8f0 head:00000000d03de848 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x200000000000840(slab|head|node=0|zone=2) page_type: 0xffffffff() raw: 0200000000000840 ffff888100042dc0 ffffea0004244400 dead000000000002 raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected

Memory state around the buggy address: ffff88810c8f3700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88810c8f3780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

ffff88810c8f3800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^ ffff88810c8f3880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88810c8f3900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================

Fix it by using a local variable to record the gendisk ID.

Fixes: 77567b25ab9f ("ubi: use blk_mq_alloc_disk and blk_cleanup_disk") Signed-off-by: ZhaoLong Wang wangzhaolong1@huawei.com Reviewed-by: Zhihao Cheng chengzhihao1@huawei.com Signed-off-by: Richard Weinberger richard@nod.at Signed-off-by: Li Nan linan122@huawei.com --- drivers/mtd/ubi/block.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c index 437c5b83ffe5..309a42aeaa4c 100644 --- a/drivers/mtd/ubi/block.c +++ b/drivers/mtd/ubi/block.c @@ -447,13 +447,15 @@ int ubiblock_create(struct ubi_volume_info *vi)

static void ubiblock_cleanup(struct ubiblock *dev) { + int id = dev->gd->first_minor; + /* Stop new requests to arrive */ del_gendisk(dev->gd); /* Finally destroy the blk queue */ dev_info(disk_to_dev(dev->gd), "released"); put_disk(dev->gd); blk_mq_free_tag_set(&dev->tag_set); - idr_remove(&ubiblock_minor_idr, dev->gd->first_minor); + idr_remove(&ubiblock_minor_idr, id); }

int ubiblock_remove(struct ubi_volume_info *vi)