* rqst[1,2,3] is allocated in vars
* each rqst->rq_iov is also allocated in vars or using pooled memory
SMB2_open_free, SMB2_ioctl_free, SMB2_query_info_free are iterating on
each rqst after vars has been freed (use-after-free), and they are
freeing the kvec a second time (double-free).
How to trigger:
* compile with KASAN
* mount a share
$ smbinfo quota /mnt/foo
Segmentation fault
$ dmesg
==================================================================
BUG: KASAN: use-after-free in SMB2_open_free+0x1c/0xa0
Read of size 8 at addr ffff888007b10c00 by task python3/1200
CPU: 2 PID: 1200 Comm: python3 Not tainted 5.12.0-rc6+ #107
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014
Call Trace:
dump_stack+0x93/0xc2
print_address_description.constprop.0+0x18/0x130
? SMB2_open_free+0x1c/0xa0
? SMB2_open_free+0x1c/0xa0
kasan_report.cold+0x7f/0x111
? smb2_ioctl_query_info+0x240/0x990
? SMB2_open_free+0x1c/0xa0
SMB2_open_free+0x1c/0xa0
smb2_ioctl_query_info+0x2bf/0x990
? smb2_query_reparse_tag+0x600/0x600
? cifs_mapchar+0x250/0x250
? rcu_read_lock_sched_held+0x3f/0x70
? cifs_strndup_to_utf16+0x12c/0x1c0
? rwlock_bug.part.0+0x60/0x60
? rcu_read_lock_sched_held+0x3f/0x70
? cifs_convert_path_to_utf16+0xf8/0x140
? smb2_check_message+0x6f0/0x6f0
cifs_ioctl+0xf18/0x16b0
? smb2_query_reparse_tag+0x600/0x600
? cifs_readdir+0x1800/0x1800
? selinux_bprm_creds_for_exec+0x4d0/0x4d0
? do_user_addr_fault+0x30b/0x950
? __x64_sys_openat+0xce/0x140
__x64_sys_ioctl+0xb9/0xf0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fdcf1f4ba87
Code: b3 66 90 48 8b 05 11 14 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 13 2c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffef1ce7748 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000c018cf07 RCX: 00007fdcf1f4ba87
RDX: 0000564c467c5590 RSI: 00000000c018cf07 RDI: 0000000000000003
RBP: 00007ffef1ce7770 R08: 00007ffef1ce7420 R09: 00007fdcf0e0562b
R10: 0000000000000100 R11: 0000000000000246 R12: 0000000000004018
R13: 0000000000000001 R14: 0000000000000003 R15: 0000564c467c5590
Allocated by task 1200:
kasan_save_stack+0x1b/0x40
__kasan_kmalloc+0x7a/0x90
smb2_ioctl_query_info+0x10e/0x990
cifs_ioctl+0xf18/0x16b0
__x64_sys_ioctl+0xb9/0xf0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xae
Freed by task 1200:
kasan_save_stack+0x1b/0x40
kasan_set_track+0x1c/0x30
kasan_set_free_info+0x20/0x30
__kasan_slab_free+0xe5/0x110
slab_free_freelist_hook+0x53/0x130
kfree+0xcc/0x320
smb2_ioctl_query_info+0x2ad/0x990
cifs_ioctl+0xf18/0x16b0
__x64_sys_ioctl+0xb9/0xf0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xae
The buggy address belongs to the object at ffff888007b10c00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
512-byte region [ffff888007b10c00, ffff888007b10e00)
The buggy address belongs to the page:
page:0000000044e14b75 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7b10
head:0000000044e14b75 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x100000000010200(slab|head)
raw: 0100000000010200 ffffea000015f500 0000000400000004 ffff888001042c80
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888007b10b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888007b10b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888007b10c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888007b10c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888007b10d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
ccd48ec3d4