Security Vulnerabilities - CVEs Published In August 2024
In the Linux kernel, the following vulnerability has been resolved:
ext4: make sure the first directory block is not a hole
The syzbot constructs a directory that has no dirblock but is non-inline,
i.e. the first directory block is a hole. And no errors are reported when
creating files in this directory in the following flow.
ext4_mknod
...
ext4_add_entry
// Read block 0
ext4_read_dirblock(dir, block, DIRENT)
bh = ext4_bread(NULL, inode, block, 0)
if (!bh && (type == INDEX || type == DIRENT_HTREE))
// The first directory block is a hole
// But type == DIRENT, so no error is reported.
After that, we get a directory block without '.' and '..' but with a valid
dentry. This may cause some code that relies on dot or dotdot (such as
make_indexed_dir()) to crash.
Therefore when ext4_read_dirblock() finds that the first directory block
is a hole report that the filesystem is corrupted and return an error to
avoid loading corrupted data from disk causing something bad.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-08-17
In the Linux kernel, the following vulnerability has been resolved:
ext4: check dot and dotdot of dx_root before making dir indexed
Syzbot reports a issue as follows:
============================================
BUG: unable to handle page fault for address: ffffed11022e24fe
PGD 23ffee067 P4D 23ffee067 PUD 0
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 PID: 5079 Comm: syz-executor306 Not tainted 6.10.0-rc5-g55027e689933 #0
Call Trace:
<TASK>
make_indexed_dir+0xdaf/0x13c0 fs/ext4/namei.c:2341
ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2451
ext4_rename fs/ext4/namei.c:3936 [inline]
ext4_rename2+0x26e5/0x4370 fs/ext4/namei.c:4214
[...]
============================================
The immediate cause of this problem is that there is only one valid dentry
for the block to be split during do_split, so split==0 results in out of
bounds accesses to the map triggering the issue.
do_split
unsigned split
dx_make_map
count = 1
split = count/2 = 0;
continued = hash2 == map[split - 1].hash;
---> map[4294967295]
The maximum length of a filename is 255 and the minimum block size is 1024,
so it is always guaranteed that the number of entries is greater than or
equal to 2 when do_split() is called.
But syzbot's crafted image has no dot and dotdot in dir, and the dentry
distribution in dirblock is as follows:
bus dentry1 hole dentry2 free
|xx--|xx-------------|...............|xx-------------|...............|
0 12 (8+248)=256 268 256 524 (8+256)=264 788 236 1024
So when renaming dentry1 increases its name_len length by 1, neither hole
nor free is sufficient to hold the new dentry, and make_indexed_dir() is
called.
In make_indexed_dir() it is assumed that the first two entries of the
dirblock must be dot and dotdot, so bus and dentry1 are left in dx_root
because they are treated as dot and dotdot, and only dentry2 is moved
to the new leaf block. That's why count is equal to 1.
Therefore add the ext4_check_dx_root() helper function to add more sanity
checks to dot and dotdot before starting the conversion to avoid the above
issue.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-08-17
In the Linux kernel, the following vulnerability has been resolved:
udf: Avoid using corrupted block bitmap buffer
When the filesystem block bitmap is corrupted, we detect the corruption
while loading the bitmap and fail the allocation with error. However the
next allocation from the same bitmap will notice the bitmap buffer is
already loaded and tries to allocate from the bitmap with mixed results
(depending on the exact nature of the bitmap corruption). Fix the
problem by using BH_verified bit to indicate whether the bitmap is valid
or not.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-08-17
In the Linux kernel, the following vulnerability has been resolved:
cifs: fix potential null pointer use in destroy_workqueue in init_cifs error path
Dan Carpenter reported a Smack static checker warning:
fs/smb/client/cifsfs.c:1981 init_cifs()
error: we previously assumed 'serverclose_wq' could be null (see line 1895)
The patch which introduced the serverclose workqueue used the wrong
oredering in error paths in init_cifs() for freeing it on errors.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-08-17
In the Linux kernel, the following vulnerability has been resolved:
drm/gma500: fix null pointer dereference in psb_intel_lvds_get_modes
In psb_intel_lvds_get_modes(), the return value of drm_mode_duplicate() is
assigned to mode, which will lead to a possible NULL pointer dereference
on failure of drm_mode_duplicate(). Add a check to avoid npd.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-08-17
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix a segment issue when downgrading gso_size
Linearize the skb when downgrading gso_size because it may trigger a
BUG_ON() later when the skb is segmented as described in [1,2].
CVSS Score
5.5
EPSS Score
0.0
Published
2024-08-17
In the Linux kernel, the following vulnerability has been resolved:
net: mediatek: Fix potential NULL pointer dereference in dummy net_device handling
Move the freeing of the dummy net_device from mtk_free_dev() to
mtk_remove().
Previously, if alloc_netdev_dummy() failed in mtk_probe(),
eth->dummy_dev would be NULL. The error path would then call
mtk_free_dev(), which in turn called free_netdev() assuming dummy_dev
was allocated (but it was not), potentially causing a NULL pointer
dereference.
By moving free_netdev() to mtk_remove(), we ensure it's only called when
mtk_probe() has succeeded and dummy_dev is fully allocated. This
addresses a potential NULL pointer dereference detected by Smatch[1].
CVSS Score
5.5
EPSS Score
0.0
Published
2024-08-17
In the Linux kernel, the following vulnerability has been resolved:
net: nexthop: Initialize all fields in dumped nexthops
struct nexthop_grp contains two reserved fields that are not initialized by
nla_put_nh_group(), and carry garbage. This can be observed e.g. with
strace (edited for clarity):
# ip nexthop add id 1 dev lo
# ip nexthop add id 101 group 1
# strace -e recvmsg ip nexthop get id 101
...
recvmsg(... [{nla_len=12, nla_type=NHA_GROUP},
[{id=1, weight=0, resvd1=0x69, resvd2=0x67}]] ...) = 52
The fields are reserved and therefore not currently used. But as they are, they
leak kernel memory, and the fact they are not just zero complicates repurposing
of the fields for new ends. Initialize the full structure.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-08-17
In the Linux kernel, the following vulnerability has been resolved:
tipc: Return non-zero value from tipc_udp_addr2str() on error
tipc_udp_addr2str() should return non-zero value if the UDP media
address is invalid. Otherwise, a buffer overflow access can occur in
tipc_media_addr_printf(). Fix this by returning 1 on an invalid UDP
media address.
CVSS Score
7.8
EPSS Score
0.0
Published
2024-08-17
In the Linux kernel, the following vulnerability has been resolved:
RDMA/iwcm: Fix a use-after-free related to destroying CM IDs
iw_conn_req_handler() associates a new struct rdma_id_private (conn_id) with
an existing struct iw_cm_id (cm_id) as follows:
conn_id->cm_id.iw = cm_id;
cm_id->context = conn_id;
cm_id->cm_handler = cma_iw_handler;
rdma_destroy_id() frees both the cm_id and the struct rdma_id_private. Make
sure that cm_work_handler() does not trigger a use-after-free by only
freeing of the struct rdma_id_private after all pending work has finished.
CVSS Score
7.8
EPSS Score
0.0
Published
2024-08-17