diff mbox series

[linux-5.4.y,1/8] Revert "loop: Check for overflow while configuring loop"

Message ID 20240307041411.3792061-2-zhanggenjian@126.com (mailing list archive)
State New, archived
Headers show
Series Fix the UAF issue caused by the loop driver | expand

Commit Message

Genjian March 7, 2024, 4:14 a.m. UTC 
From: Genjian Zhang <zhanggenjian@kylinos.cn>

This reverts commit 13b2856037a651ba3ab4a8b25ecab3e791926da3.

This patch lost a unlock loop_ctl_mutex in loop_get_status(...),
which caused syzbot to report a UAF issue.The upstream patch does not
have this issue. Therefore, we revert this patch and directly apply
the upstream patch later on.

Risk use-after-free as reported by syzbot：

[   84.669496] ==================================================================
[   84.670021] BUG: KASAN: use-after-free in __mutex_lock.isra.9+0xc13/0xcb0
[   84.670433] Read of size 4 at addr ffff88808dba43b8 by task syz-executor.22/14230
[   84.670885]
[   84.670987] CPU: 1 PID: 14230 Comm: syz-executor.22 Not tainted 5.4.270 #4
[   84.671397] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1kylin1 04/01/2014
[   84.671927] Call Trace:
[   84.672085]  dump_stack+0x94/0xc7
[   84.672293]  ? __mutex_lock.isra.9+0xc13/0xcb0
[   84.672569]  print_address_description.constprop.6+0x16/0x220
[   84.672915]  ? __mutex_lock.isra.9+0xc13/0xcb0
[   84.673187]  ? __mutex_lock.isra.9+0xc13/0xcb0
[   84.673462]  __kasan_report.cold.9+0x1a/0x32
[   84.673723]  ? __mutex_lock.isra.9+0xc13/0xcb0
[   84.673993]  kasan_report+0x10/0x20
[   84.674208]  __mutex_lock.isra.9+0xc13/0xcb0
[   84.674468]  ? __mutex_lock.isra.9+0x617/0xcb0
[   84.674739]  ? ww_mutex_lock_interruptible+0x100/0x100
[   84.675055]  ? ww_mutex_lock_interruptible+0x100/0x100
[   84.675369]  ? kobject_get_unless_zero+0x144/0x190
[   84.675668]  ? kobject_del+0x60/0x60
[   84.675893]  ? __module_get+0x120/0x120
[   84.676128]  ? __mutex_lock_slowpath+0x10/0x10
[   84.676399]  mutex_lock_killable+0xde/0xf0
[   84.676652]  ? __mutex_lock_killable_slowpath+0x10/0x10
[   84.676967]  ? __mutex_lock_slowpath+0x10/0x10
[   84.677243]  ? disk_block_events+0x1d/0x120
[   84.677509]  lo_open+0x16/0xc0
[   84.677701]  ? lo_compat_ioctl+0x160/0x160
[   84.677954]  __blkdev_get+0xb0f/0x1160
[   84.678185]  ? bd_may_claim+0xd0/0xd0
[   84.678410]  ? bdev_disk_changed+0x190/0x190
[   84.678674]  ? _raw_spin_lock+0x7c/0xd0
[   84.678915]  ? _raw_write_lock_bh+0xd0/0xd0
[   84.679172]  blkdev_get+0x9b/0x290
[   84.679381]  ? ihold+0x1a/0x40
[   84.679574]  blkdev_open+0x1bd/0x240
[   84.679794]  do_dentry_open+0x439/0x1000
[   84.680035]  ? blkdev_get_by_dev+0x60/0x60
[   84.680286]  ? __x64_sys_fchdir+0x1a0/0x1a0
[   84.680557]  ? inode_permission+0x86/0x320
[   84.680814]  path_openat+0x998/0x4120
[   84.681044]  ? stack_trace_consume_entry+0x160/0x160
[   84.681348]  ? do_futex+0x136/0x1880
[   84.681568]  ? path_mountpoint+0xb50/0xb50
[   84.681823]  ? save_stack+0x4d/0x80
[   84.682038]  ? save_stack+0x19/0x80
[   84.682253]  ? __kasan_kmalloc.constprop.6+0xc1/0xd0
[   84.682553]  ? kmem_cache_alloc+0xc7/0x210
[   84.682804]  ? getname_flags+0xc4/0x560
[   84.683045]  ? do_sys_open+0x1ce/0x450
[   84.683272]  ? do_syscall_64+0x9a/0x330
[   84.683509]  ? entry_SYSCALL_64_after_hwframe+0x5c/0xc1
[   84.683826]  ? _raw_spin_lock+0x7c/0xd0
[   84.684063]  ? _raw_write_lock_bh+0xd0/0xd0
[   84.684319]  ? futex_exit_release+0x60/0x60
[   84.684574]  ? kasan_unpoison_shadow+0x30/0x40
[   84.684844]  ? __kasan_kmalloc.constprop.6+0xc1/0xd0
[   84.685149]  ? get_partial_node.isra.83.part.84+0x1e5/0x340
[   84.685485]  ? __fget_light+0x1d1/0x550
[   84.685721]  do_filp_open+0x197/0x270
[   84.685946]  ? may_open_dev+0xd0/0xd0
[   84.686172]  ? kasan_unpoison_shadow+0x30/0x40
[   84.686443]  ? __kasan_kmalloc.constprop.6+0xc1/0xd0
[   84.686743]  ? __alloc_fd+0x1a3/0x580
[   84.686973]  do_sys_open+0x2c7/0x450
[   84.687195]  ? filp_open+0x60/0x60
[   84.687406]  ? __x64_sys_timer_settime32+0x280/0x280
[   84.687707]  do_syscall_64+0x9a/0x330
[   84.687931]  ? syscall_return_slowpath+0x17a/0x230
[   84.688221]  entry_SYSCALL_64_after_hwframe+0x5c/0xc1
[   84.688524]
[   84.688622] Allocated by task 14056:
[   84.688842]  save_stack+0x19/0x80
[   84.689044]  __kasan_kmalloc.constprop.6+0xc1/0xd0
[   84.689333]  kmem_cache_alloc_node+0xe2/0x230
[   84.689600]  copy_process+0x165c/0x72d0
[   84.689833]  _do_fork+0xf9/0x9a0
[   84.690032]  __x64_sys_clone+0x17a/0x200
[   84.690271]  do_syscall_64+0x9a/0x330
[   84.690496]  entry_SYSCALL_64_after_hwframe+0x5c/0xc1
[   84.690800]
[   84.690903] Freed by task 0:
[   84.691081]  save_stack+0x19/0x80
[   84.691287]  __kasan_slab_free+0x125/0x170
[   84.691535]  kmem_cache_free+0x7a/0x2a0
[   84.691774]  __put_task_struct+0x1ec/0x4a0
[   84.692023]  delayed_put_task_struct+0x178/0x1d0
[   84.692303]  rcu_core+0x538/0x16c0
[   84.692512]  __do_softirq+0x175/0x63d
[   84.692741]
[   84.692840] The buggy address belongs to the object at ffff88808dba4380
[   84.692840]  which belongs to the cache task_struct of size 3328
[   84.693584] The buggy address is located 56 bytes inside of
[   84.693584]  3328-byte region [ffff88808dba4380, ffff88808dba5080)
[   84.694272] The buggy address belongs to the page:
[   84.694563] page:ffffea000236e800 refcount:1 mapcount:0 mapping:ffff8881838acdc0 index:0x0 compound_mapcount: 0
[   84.695166] flags: 0x100000000010200(slab|head)
[   84.695457] raw: 0100000000010200 dead000000000100 dead000000000122 ffff8881838acdc0
[   84.695919] raw: 0000000000000000 0000000000090009 00000001ffffffff 0000000000000000
[   84.696375] page dumped because: kasan: bad access detected
[   84.696705]
[   84.696801] Memory state around the buggy address:
[   84.697089]  ffff88808dba4280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   84.697519]  ffff88808dba4300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[   84.697945] >ffff88808dba4380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   84.698371]                                         ^
[   84.698674]  ffff88808dba4400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   84.699111]  ffff88808dba4480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   84.699537] ==================================================================
[   84.699965] Disabling lock debugging due to kernel taint

Reported-by: k2ci <kernel-bot@kylinos.cn>
Signed-off-by: Genjian Zhang <zhanggenjian@kylinos.cn>
---
 drivers/block/loop.c | 5 -----
 1 file changed, 5 deletions(-)
diff mbox series

Patch

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index d8821c9cb170..fced67ab1068 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1397,11 +1397,6 @@  loop_get_status(struct loop_device *lo, struct loop_info64 *info)
 	info->lo_number = lo->lo_number;
 	info->lo_offset = lo->lo_offset;
 	info->lo_sizelimit = lo->lo_sizelimit;
-
-	/* loff_t vars have been assigned __u64 */
-	if (lo->lo_offset < 0 || lo->lo_sizelimit < 0)
-		return -EOVERFLOW;
-
 	info->lo_flags = lo->lo_flags;
 	memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
 	memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);