In the Linux kernel, the following vulnerability has been resolved:
ipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr
Although ipv6_get_ifaddr walks inet6_addr_lst under the RCU lock, it
still means hlist_for_each_entry_rcu can return an item that got removed
from the list. The memory itself of such item is not freed thanks to RCU
but nothing guarantees the actual content of the memory is sane.
In particular, the reference count can be zero. This can happen if
ipv6_del_addr is called in parallel. ipv6_del_addr removes the entry
from inet6_addr_lst (hlist_del_init_rcu(&ifp->addr_lst)) and drops all
references (__in6_ifa_put(ifp) + in6_ifa_put(ifp)). With bad enough
timing, this can happen:
1. In ipv6_get_ifaddr, hlist_for_each_entry_rcu returns an entry.
2. Then, the whole ipv6_del_addr is executed for the given entry. The
reference count drops to zero and kfree_rcu is scheduled.
3. ipv6_get_ifaddr continues and tries to increments the reference count
(in6_ifa_hold).
4. The rcu is unlocked and the entry is freed.
5. The freed entry is returned.
Prevent increasing of the reference count in such case. The name
in6_ifa_hold_safe is chosen to mimic the existing fib6_info_hold_safe.
[ 41.506330] refcount_t: addition on 0; use-after-free.
[ 41.506760] WARNING: CPU: 0 PID: 595 at lib/refcount.c:25 refcount_warn_saturate+0xa5/0x130
[ 41.507413] Modules linked in: veth bridge stp llc
[ 41.507821] CPU: 0 PID: 595 Comm: python3 Not tainted 6.9.0-rc2.main-00208-g49563be82afa #14
[ 41.508479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
[ 41.509163] RIP: 0010:refcount_warn_saturate+0xa5/0x130
[ 41.509586] Code: ad ff 90 0f 0b 90 90 c3 cc cc cc cc 80 3d c0 30 ad 01 00 75 a0 c6 05 b7 30 ad 01 01 90 48 c7 c7 38 cc 7a 8c e8 cc 18 ad ff 90 <0f> 0b 90 90 c3 cc cc cc cc 80 3d 98 30 ad 01 00 0f 85 75 ff ff ff
[ 41.510956] RSP: 0018:ffffbda3c026baf0 EFLAGS: 00010282
[ 41.511368] RAX: 0000000000000000 RBX: ffff9e9c46914800 RCX: 0000000000000000
[ 41.511910] RDX: ffff9e9c7ec29c00 RSI: ffff9e9c7ec1c900 RDI: ffff9e9c7ec1c900
[ 41.512445] RBP: ffff9e9c43660c9c R08: 0000000000009ffb R09: 00000000ffffdfff
[ 41.512998] R10: 00000000ffffdfff R11: ffffffff8ca58a40 R12: ffff9e9c4339a000
[ 41.513534] R13: 0000000000000001 R14: ffff9e9c438a0000 R15: ffffbda3c026bb48
[ 41.514086] FS: 00007fbc4cda1740(0000) GS:ffff9e9c7ec00000(0000) knlGS:0000000000000000
[ 41.514726] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 41.515176] CR2: 000056233b337d88 CR3: 000000000376e006 CR4: 0000000000370ef0
[ 41.515713] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 41.516252] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 41.516799] Call Trace:
[ 41.517037] <TASK>
[ 41.517249] ? __warn+0x7b/0x120
[ 41.517535] ? refcount_warn_saturate+0xa5/0x130
[ 41.517923] ? report_bug+0x164/0x190
[ 41.518240] ? handle_bug+0x3d/0x70
[ 41.518541] ? exc_invalid_op+0x17/0x70
[ 41.520972] ? asm_exc_invalid_op+0x1a/0x20
[ 41.521325] ? refcount_warn_saturate+0xa5/0x130
[ 41.521708] ipv6_get_ifaddr+0xda/0xe0
[ 41.522035] inet6_rtm_getaddr+0x342/0x3f0
[ 41.522376] ? __pfx_inet6_rtm_getaddr+0x10/0x10
[ 41.522758] rtnetlink_rcv_msg+0x334/0x3d0
[ 41.523102] ? netlink_unicast+0x30f/0x390
[ 41.523445] ? __pfx_rtnetlink_rcv_msg+0x10/0x10
[ 41.523832] netlink_rcv_skb+0x53/0x100
[ 41.524157] netlink_unicast+0x23b/0x390
[ 41.524484] netlink_sendmsg+0x1f2/0x440
[ 41.524826] __sys_sendto+0x1d8/0x1f0
[ 41.525145] __x64_sys_sendto+0x1f/0x30
[ 41.525467] do_syscall_64+0xa5/0x1b0
[ 41.525794] entry_SYSCALL_64_after_hwframe+0x72/0x7a
[ 41.526213] RIP: 0033:0x7fbc4cfcea9a
[ 41.526528] Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 15 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7e c3 0f 1f 44 00 00 41 54 48 83 ec 30 44 89
[ 41.527942] RSP: 002b:00007f
---truncated---
In the Linux kernel, the following vulnerability has been resolved:
drm/client: Fully protect modes[] with dev->mode_config.mutex
The modes[] array contains pointers to modes on the connectors'
mode lists, which are protected by dev->mode_config.mutex.
Thus we need to extend modes[] the same protection or by the
time we use it the elements may already be pointing to
freed/reused memory.
In the Linux kernel, the following vulnerability has been resolved:
kprobes: Fix possible use-after-free issue on kprobe registration
When unloading a module, its state is changing MODULE_STATE_LIVE ->
MODULE_STATE_GOING -> MODULE_STATE_UNFORMED. Each change will take
a time. `is_module_text_address()` and `__module_text_address()`
works with MODULE_STATE_LIVE and MODULE_STATE_GOING.
If we use `is_module_text_address()` and `__module_text_address()`
separately, there is a chance that the first one is succeeded but the
next one is failed because module->state becomes MODULE_STATE_UNFORMED
between those operations.
In `check_kprobe_address_safe()`, if the second `__module_text_address()`
is failed, that is ignored because it expected a kernel_text address.
But it may have failed simply because module->state has been changed
to MODULE_STATE_UNFORMED. In this case, arm_kprobe() will try to modify
non-exist module text address (use-after-free).
To fix this problem, we should not use separated `is_module_text_address()`
and `__module_text_address()`, but use only `__module_text_address()`
once and do `try_module_get(module)` which is only available with
MODULE_STATE_LIVE.
In the Linux kernel, the following vulnerability has been resolved:
dyndbg: fix old BUG_ON in >control parser
Fix a BUG_ON from 2009. Even if it looks "unreachable" (I didn't
really look), lets make sure by removing it, doing pr_err and return
-EINVAL instead.
In the Linux kernel, the following vulnerability has been resolved:
VMCI: Fix memcpy() run-time warning in dg_dispatch_as_host()
Syzkaller hit 'WARNING in dg_dispatch_as_host' bug.
memcpy: detected field-spanning write (size 56) of single field "&dg_info->msg"
at drivers/misc/vmw_vmci/vmci_datagram.c:237 (size 24)
WARNING: CPU: 0 PID: 1555 at drivers/misc/vmw_vmci/vmci_datagram.c:237
dg_dispatch_as_host+0x88e/0xa60 drivers/misc/vmw_vmci/vmci_datagram.c:237
Some code commentry, based on my understanding:
544 #define VMCI_DG_SIZE(_dg) (VMCI_DG_HEADERSIZE + (size_t)(_dg)->payload_size)
/// This is 24 + payload_size
memcpy(&dg_info->msg, dg, dg_size);
Destination = dg_info->msg ---> this is a 24 byte
structure(struct vmci_datagram)
Source = dg --> this is a 24 byte structure (struct vmci_datagram)
Size = dg_size = 24 + payload_size
{payload_size = 56-24 =32} -- Syzkaller managed to set payload_size to 32.
35 struct delayed_datagram_info {
36 struct datagram_entry *entry;
37 struct work_struct work;
38 bool in_dg_host_queue;
39 /* msg and msg_payload must be together. */
40 struct vmci_datagram msg;
41 u8 msg_payload[];
42 };
So those extra bytes of payload are copied into msg_payload[], a run time
warning is seen while fuzzing with Syzkaller.
One possible way to fix the warning is to split the memcpy() into
two parts -- one -- direct assignment of msg and second taking care of payload.
Gustavo quoted:
"Under FORTIFY_SOURCE we should not copy data across multiple members
in a structure."
In the Linux kernel, the following vulnerability has been resolved:
scsi: lpfc: Fix possible memory leak in lpfc_rcv_padisc()
The call to lpfc_sli4_resume_rpi() in lpfc_rcv_padisc() may return an
unsuccessful status. In such cases, the elsiocb is not issued, the
completion is not called, and thus the elsiocb resource is leaked.
Check return value after calling lpfc_sli4_resume_rpi() and conditionally
release the elsiocb resource.
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: btintel: Fix null ptr deref in btintel_read_version
If hci_cmd_sync_complete() is triggered and skb is NULL, then
hdev->req_skb is NULL, which will cause this issue.
In the Linux kernel, the following vulnerability has been resolved:
btrfs: send: handle path ref underflow in header iterate_inode_ref()
Change BUG_ON to proper error handling if building the path buffer
fails. The pointers are not printed so we don't accidentally leak kernel
addresses.
In the Linux kernel, the following vulnerability has been resolved:
btrfs: handle chunk tree lookup error in btrfs_relocate_sys_chunks()
The unhandled case in btrfs_relocate_sys_chunks() loop is a corruption,
as it could be caused only by two impossible conditions:
- at first the search key is set up to look for a chunk tree item, with
offset -1, this is an inexact search and the key->offset will contain
the correct offset upon a successful search, a valid chunk tree item
cannot have an offset -1
- after first successful search, the found_key corresponds to a chunk
item, the offset is decremented by 1 before the next loop, it's
impossible to find a chunk item there due to alignment and size
constraints