Linux: >> Linux Kernel >> 6.1.0 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
cachefiles: cyclic allocation of msg_id to avoid reuse
Reusing the msg_id after a maliciously completed reopen request may cause
a read request to remain unprocessed and result in a hung, as shown below:
t1 | t2 | t3
-------------------------------------------------
cachefiles_ondemand_select_req
cachefiles_ondemand_object_is_close(A)
cachefiles_ondemand_set_object_reopening(A)
queue_work(fscache_object_wq, &info->work)
ondemand_object_worker
cachefiles_ondemand_init_object(A)
cachefiles_ondemand_send_req(OPEN)
// get msg_id 6
wait_for_completion(&req_A->done)
cachefiles_ondemand_daemon_read
// read msg_id 6 req_A
cachefiles_ondemand_get_fd
copy_to_user
// Malicious completion msg_id 6
copen 6,-1
cachefiles_ondemand_copen
complete(&req_A->done)
// will not set the object to close
// because ondemand_id && fd is valid.
// ondemand_object_worker() is done
// but the object is still reopening.
// new open req_B
cachefiles_ondemand_init_object(B)
cachefiles_ondemand_send_req(OPEN)
// reuse msg_id 6
process_open_req
copen 6,A.size
// The expected failed copen was executed successfully
Expect copen to fail, and when it does, it closes fd, which sets the
object to close, and then close triggers reopen again. However, due to
msg_id reuse resulting in a successful copen, the anonymous fd is not
closed until the daemon exits. Therefore read requests waiting for reopen
to complete may trigger hung task.
To avoid this issue, allocate the msg_id cyclically to avoid reusing the
msg_id for a very short duration of time.
CVSS Score
7.8
EPSS Score
0.0
Published
2024-07-29
In the Linux kernel, the following vulnerability has been resolved:
bpf: Defer work in bpf_timer_cancel_and_free
Currently, the same case as previous patch (two timer callbacks trying
to cancel each other) can be invoked through bpf_map_update_elem as
well, or more precisely, freeing map elements containing timers. Since
this relies on hrtimer_cancel as well, it is prone to the same deadlock
situation as the previous patch.
It would be sufficient to use hrtimer_try_to_cancel to fix this problem,
as the timer cannot be enqueued after async_cancel_and_free. Once
async_cancel_and_free has been done, the timer must be reinitialized
before it can be armed again. The callback running in parallel trying to
arm the timer will fail, and freeing bpf_hrtimer without waiting is
sufficient (given kfree_rcu), and bpf_timer_cb will return
HRTIMER_NORESTART, preventing the timer from being rearmed again.
However, there exists a UAF scenario where the callback arms the timer
before entering this function, such that if cancellation fails (due to
timer callback invoking this routine, or the target timer callback
running concurrently). In such a case, if the timer expiration is
significantly far in the future, the RCU grace period expiration
happening before it will free the bpf_hrtimer state and along with it
the struct hrtimer, that is enqueued.
Hence, it is clear cancellation needs to occur after
async_cancel_and_free, and yet it cannot be done inline due to deadlock
issues. We thus modify bpf_timer_cancel_and_free to defer work to the
global workqueue, adding a work_struct alongside rcu_head (both used at
_different_ points of time, so can share space).
Update existing code comments to reflect the new state of affairs.
CVSS Score
7.8
EPSS Score
0.0
Published
2024-07-29
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: discard write access to the directory open
may_open() does not allow a directory to be opened with the write access.
However, some writing flags set by client result in adding write access
on server, making ksmbd incompatible with FUSE file system. Simply, let's
discard the write access when opening a directory.
list_add corruption. next is NULL.
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:26!
pc : __list_add_valid+0x88/0xbc
lr : __list_add_valid+0x88/0xbc
Call trace:
__list_add_valid+0x88/0xbc
fuse_finish_open+0x11c/0x170
fuse_open_common+0x284/0x5e8
fuse_dir_open+0x14/0x24
do_dentry_open+0x2a4/0x4e0
dentry_open+0x50/0x80
smb2_open+0xbe4/0x15a4
handle_ksmbd_work+0x478/0x5ec
process_one_work+0x1b4/0x448
worker_thread+0x25c/0x430
kthread+0x104/0x1d4
ret_from_fork+0x10/0x20
CVSS Score
5.5
EPSS Score
0.0
Published
2024-07-29
In the Linux kernel, the following vulnerability has been resolved:
filelock: Fix fcntl/close race recovery compat path
When I wrote commit 3cad1bc01041 ("filelock: Remove locks reliably when
fcntl/close race is detected"), I missed that there are two copies of the
code I was patching: The normal version, and the version for 64-bit offsets
on 32-bit kernels.
Thanks to Greg KH for stumbling over this while doing the stable
backport...
Apply exactly the same fix to the compat path for 32-bit kernels.
CVSS Score
4.7
EPSS Score
0.0
Published
2024-07-29
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: Validate ff offset
This adds sanity checks for ff offset. There is a check
on rt->first_free at first, but walking through by ff
without any check. If the second ff is a large offset.
We may encounter an out-of-bound read.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-07-29
In the Linux kernel, the following vulnerability has been resolved:
tap: add missing verification for short frame
The cited commit missed to check against the validity of the frame length
in the tap_get_user_xdp() path, which could cause a corrupted skb to be
sent downstack. Even before the skb is transmitted, the
tap_get_user_xdp()-->skb_set_network_header() may assume the size is more
than ETH_HLEN. Once transmitted, this could either cause out-of-bound
access beyond the actual length, or confuse the underlayer with incorrect
or inconsistent header length in the skb metadata.
In the alternative path, tap_get_user() already prohibits short frame which
has the length less than Ethernet header size from being transmitted.
This is to drop any frame shorter than the Ethernet header size just like
how tap_get_user() does.
CVE: CVE-2024-41090
CVSS Score
7.1
EPSS Score
0.0
Published
2024-07-29
In the Linux kernel, the following vulnerability has been resolved:
tun: add missing verification for short frame
The cited commit missed to check against the validity of the frame length
in the tun_xdp_one() path, which could cause a corrupted skb to be sent
downstack. Even before the skb is transmitted, the
tun_xdp_one-->eth_type_trans() may access the Ethernet header although it
can be less than ETH_HLEN. Once transmitted, this could either cause
out-of-bound access beyond the actual length, or confuse the underlayer
with incorrect or inconsistent header length in the skb metadata.
In the alternative path, tun_get_user() already prohibits short frame which
has the length less than Ethernet header size from being transmitted for
IFF_TAP.
This is to drop any frame shorter than the Ethernet header size just like
how tun_get_user() does.
CVE: CVE-2024-41091
CVSS Score
7.1
EPSS Score
0.0
Published
2024-07-29
In the Linux kernel, the following vulnerability has been resolved:
ocfs2: add bounds checking to ocfs2_check_dir_entry()
This adds sanity checks for ocfs2_dir_entry to make sure all members of
ocfs2_dir_entry don't stray beyond valid memory region.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-07-29
In the Linux kernel, the following vulnerability has been resolved:
ocfs2: strict bound check before memcmp in ocfs2_xattr_find_entry()
xattr in ocfs2 maybe 'non-indexed', which saved with additional space
requested. It's better to check if the memory is out of bound before
memcmp, although this possibility mainly comes from crafted poisonous
images.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-07-29
In the Linux kernel, the following vulnerability has been resolved:
jfs: don't walk off the end of ealist
Add a check before visiting the members of ea to
make sure each ea stays within the ealist.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-07-29