CVE-2022-48913

In the Linux kernel, the following vulnerability has been resolved:

blktrace: fix use after free for struct blk_trace

When tracing the whole disk, 'dropped' and 'msg' will be created

under 'q->debugfs_dir' and 'bt->dir' is NULL, thus blk_trace_free()

won't remove those files. What's worse, the following UAF can be

triggered because of accessing stale 'dropped' and 'msg':

==================================================================

BUG: KASAN: use-after-free in blk_dropped_read+0x89/0x100

Read of size 4 at addr ffff88816912f3d8 by task blktrace/1188

CPU: 27 PID: 1188 Comm: blktrace Not tainted 5.17.0-rc4-next-20220217+ #469

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-4

Call Trace:

<TASK>

dump_stack_lvl+0x34/0x44

print_address_description.constprop.0.cold+0xab/0x381

? blk_dropped_read+0x89/0x100

? blk_dropped_read+0x89/0x100

kasan_report.cold+0x83/0xdf

? blk_dropped_read+0x89/0x100

kasan_check_range+0x140/0x1b0

blk_dropped_read+0x89/0x100

? blk_create_buf_file_callback+0x20/0x20

? kmem_cache_free+0xa1/0x500

? do_sys_openat2+0x258/0x460

full_proxy_read+0x8f/0xc0

vfs_read+0xc6/0x260

ksys_read+0xb9/0x150

? vfs_write+0x3d0/0x3d0

? fpregs_assert_state_consistent+0x55/0x60

? exit_to_user_mode_prepare+0x39/0x1e0

do_syscall_64+0x35/0x80

entry_SYSCALL_64_after_hwframe+0x44/0xae

RIP: 0033:0x7fbc080d92fd

Code: ce 20 00 00 75 10 b8 00 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 83 1

RSP: 002b:00007fbb95ff9cb0 EFLAGS: 00000293 ORIG_RAX: 0000000000000000

RAX: ffffffffffffffda RBX: 00007fbb95ff9dc0 RCX: 00007fbc080d92fd

RDX: 0000000000000100 RSI: 00007fbb95ff9cc0 RDI: 0000000000000045

RBP: 0000000000000045 R08: 0000000000406299 R09: 00000000fffffffd

R10: 000000000153afa0 R11: 0000000000000293 R12: 00007fbb780008c0

R13: 00007fbb78000938 R14: 0000000000608b30 R15: 00007fbb780029c8

</TASK>

Allocated by task 1050:

kasan_save_stack+0x1e/0x40

__kasan_kmalloc+0x81/0xa0

do_blk_trace_setup+0xcb/0x410

__blk_trace_setup+0xac/0x130

blk_trace_ioctl+0xe9/0x1c0

blkdev_ioctl+0xf1/0x390

__x64_sys_ioctl+0xa5/0xe0

do_syscall_64+0x35/0x80

entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 1050:

kasan_save_stack+0x1e/0x40

kasan_set_track+0x21/0x30

kasan_set_free_info+0x20/0x30

__kasan_slab_free+0x103/0x180

kfree+0x9a/0x4c0

__blk_trace_remove+0x53/0x70

blk_trace_ioctl+0x199/0x1c0

blkdev_common_ioctl+0x5e9/0xb30

blkdev_ioctl+0x1a5/0x390

__x64_sys_ioctl+0xa5/0xe0

do_syscall_64+0x35/0x80

entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88816912f380

which belongs to the cache kmalloc-96 of size 96

The buggy address is located 88 bytes inside of

96-byte region [ffff88816912f380, ffff88816912f3e0)

The buggy address belongs to the page:

page:000000009a1b4e7c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0f

flags: 0x17ffffc0000200(slab|node=0|zone=2|lastcpupid=0x1fffff)

raw: 0017ffffc0000200 ffffea00044f1100 dead000000000002 ffff88810004c780

raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff88816912f280: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc

ffff88816912f300: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc

>ffff88816912f380: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc

^

ffff88816912f400: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc

ffff88816912f480: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc

==================================================================