Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Local
0

CVE-2021-4442

Disclosure Date: August 29, 2024 •
CVE-2021-4442 CVSS v3 Base Score: 5.5
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

In the Linux kernel, the following vulnerability has been resolved:

tcp: add sanity tests to TCP_QUEUE_SEQ

Qingyu Li reported a syzkaller bug where the repro
changes RCV SEQ after restoring data in the receive queue.

mprotect(0x4aa000, 12288, PROT_READ) = 0
mmap(0x1ffff000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x1ffff000
mmap(0x20000000, 16777216, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x20000000
mmap(0x21000000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x21000000
socket(AF_INET6, SOCK_STREAM, IPPROTO_IP) = 3
setsockopt(3, SOL_TCP, TCP_REPAIR, [1], 4) = 0
connect(3, {sa_family=AF_INET6, sin6_port=htons(0), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, “::1”, &sin6_addr), sin6_scope_id=0}, 28) = 0
setsockopt(3, SOL_TCP, TCP_REPAIR_QUEUE, [1], 4) = 0
sendmsg(3, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base=“0x0000000000000003\0\0”, iov_len=20}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 20
setsockopt(3, SOL_TCP, TCP_REPAIR, [0], 4) = 0
setsockopt(3, SOL_TCP, TCP_QUEUE_SEQ, [128], 4) = 0
recvfrom(3, NULL, 20, 0, NULL, NULL) = -1 ECONNRESET (Connection reset by peer)

syslog shows:
[ 111.205099] TCP recvmsg seq # bug 2: copied 80, seq 0, rcvnxt 80, fl 0
[ 111.207894] WARNING: CPU: 1 PID: 356 at net/ipv4/tcp.c:2343 tcp_recvmsg_locked+0x90e/0x29a0

This should not be allowed. TCP_QUEUE_SEQ should only be used
when queues are empty.

This patch fixes this case, and the tx path as well.

Add Assessment

No one has assessed this topic. Be the first to add your voice to the community.

CVSS V3 Severity and Metrics
Base Score:
5.5 Medium
Impact Score:
3.6
Exploitability Score:
1.8
Vector:
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector (AV):
Local
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
None
Integrity (I):
None
Availability (A):
High

General Information

Offensive Application
Unknown
Utility Class
Unknown
Ports
Unknown
OS
Unknown
Vulnerable Versions
Linux 319f460237fc
Linux not down converted
Prerequisites
Unknown
Discovered By
Unknown
PoC Author
Unknown
Metasploit Module
Unknown
Reporter
Unknown

Vendors

  • linux

Products

  • linux kernel,
  • linux kernel 5.12
Technical Analysis