Unknown
CVE-2024-40955
CVE ID
AttackerKB requires a CVE ID in order to pull vulnerability data and references from the CVE list and the National Vulnerability Database. If available, please supply below:
Add References:
CVE-2024-40955
MITRE ATT&CK
Collection
Command and Control
Credential Access
Defense Evasion
Discovery
Execution
Exfiltration
Impact
Initial Access
Lateral Movement
Persistence
Privilege Escalation
Topic Tags
Description
In the Linux kernel, the following vulnerability has been resolved:
ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists()
We can trigger a slab-out-of-bounds with the following commands:
mkfs.ext4 -F /dev/$disk 10G mount /dev/$disk /tmp/test echo 2147483647 > /sys/fs/ext4/$disk/mb_group_prealloc echo test > /tmp/test/file && sync
==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4]
Read of size 8 at addr ffff888121b9d0f0 by task kworker/u2:0/11
CPU: 0 PID: 11 Comm: kworker/u2:0 Tainted: GL 6.7.0-next-20240118 #521
Call Trace:
dump_stack_lvl+0x2c/0x50
kasan_report+0xb6/0xf0
ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4]
ext4_mb_regular_allocator+0x19e9/0x2370 [ext4]
ext4_mb_new_blocks+0x88a/0x1370 [ext4]
ext4_ext_map_blocks+0x14f7/0x2390 [ext4]
ext4_map_blocks+0x569/0xea0 [ext4]
ext4_do_writepages+0x10f6/0x1bc0 [ext4]
[…]
The flow of issue triggering is as follows:
// Set s_mb_group_prealloc to 2147483647 via sysfs
ext4_mb_new_blocks
ext4_mb_normalize_request
ext4_mb_normalize_group_request ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc
ext4_mb_regular_allocator
ext4_mb_choose_next_group ext4_mb_choose_next_group_best_avail mb_avg_fragment_size_order order = fls(len) - 2 = 29 ext4_mb_find_good_group_avg_frag_lists frag_list = &sbi->s_mb_avg_fragment_size[order] if (list_empty(frag_list)) // Trigger SOOB!
At 4k block size, the length of the s_mb_avg_fragment_size list is 14,
but an oversized s_mb_group_prealloc is set, causing slab-out-of-bounds
to be triggered by an attempt to access an element at index 29.
Add a new attr_id attr_clusters_in_group with values in the range
[0, sbi->s_clusters_per_group] and declare mb_group_prealloc as
that type to fix the issue. In addition avoid returning an order
from mb_avg_fragment_size_order() greater than MB_NUM_ORDERS(sb)
and reduce some useless loops.
Add Assessment
No one has assessed this topic. Be the first to add your voice to the community.
CVSS V3 Severity and Metrics
General Information
Vendors
- linux
Products
- linux kernel
References
Additional Info
Technical Analysis
Report as Emergent Threat Response
Report as Exploited in the Wild
CVE ID
AttackerKB requires a CVE ID in order to pull vulnerability data and references from the CVE list and the National Vulnerability Database. If available, please supply below:
