CyberSecBulletin
CVE-2024-26589NVD status: Modified

Linux: Improper Restriction of Operations within the Bounds of a Memory Buffer

Published Updated By the CyberSecBulletin desk

CVE-2024-26589 is a high-severity improper restriction of operations within the bounds of a memory buffer vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 7856cb9f0d795ce518a44c5d135dd932cfbfc656, 29ffa63f21bcdcef3e36b03cccf9d0cd031f6ab0, 4108b86e324da42f7ed425bd71632fd844300dc8 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.24% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 7856cb9f0d795ce518a44c5d135dd932cfbfc656 or 29ffa63f21bcdcef3e36b03cccf9d0cd031f6ab0 or 4108b86e324da42f7ed425bd71632fd844300dc8 or e8d3872b617c21100c5ee4f64e513997a68c2e3d, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.15.148 or 6.1.75 or 6.6.14 or 6.7.2, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxd58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9 up to, but not including, 7856cb9f0d795ce518a44c5d135dd932cfbfc656; d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9 up to, but not including, 29ffa63f21bcdcef3e36b03cccf9d0cd031f6ab0; d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9 up to, but not including, 4108b86e324da42f7ed425bd71632fd844300dc8; d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9 up to, but not including, e8d3872b617c21100c5ee4f64e513997a68c2e3d; d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9 up to, but not including, 1b500d5d6cecf98dd6ca88bc9e7ae1783c83e6d3; d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9 up to, but not including, 22c7fa171a02d310e3a3f6ed46a698ca8a0060ed; 4.207856cb9f0d795ce518a44c5d135dd932cfbfc656, 29ffa63f21bcdcef3e36b03cccf9d0cd031f6ab0, 4108b86e324da42f7ed425bd71632fd844300dc8, e8d3872b617c21100c5ee4f64e513997a68c2e3d, 1b500d5d6cecf98dd6ca88bc9e7ae1783c83e6d3, 22c7fa171a02d310e3a3f6ed46a698ca8a0060ed
LinuxLinux Kernel4.20 up to, but not including, 5.15.148; 5.16.0 up to, but not including, 6.1.75; 6.2.0 up to, but not including, 6.6.14; 6.7.0 up to, but not including, 6.7.25.15.148, 6.1.75, 6.6.14, 6.7.2

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject variable offset alu on PTR_TO_FLOW_KEYS For PTR_TO_FLOW_KEYS, check_flow_keys_access() only uses fixed off for validation. However, variable offset ptr alu is not prohibited for this ptr kind. So the variable offset is not checked. The following prog is accepted: func#0 @0 0: R1=ctx() R10=fp0 0: (bf) r6 = r1 ; R1=ctx() R6_w=ctx() 1: (79) r7 = *(u64 *)(r6 +144) ; R6_w=ctx() R7_w=flow_keys() 2: (b7) r8 = 1024 ; R8_w=1024 3: (37) r8 /= 1 ; R8_w=scalar() 4: (57) r8 &= 1024 ; R8_w=scalar(smin=smin32=0, smax=umax=smax32=umax32=1024,var_off=(0x0; 0x400)) 5: (0f) r7 += r8 mark_precise: frame0: last_idx 5 first_idx 0 subseq_idx -1 mark_precise: frame0: regs=r8 stack= before 4: (57) r8 &= 1024 mark_precise: frame0: regs=r8 stack= before 3: (37) r8 /= 1 mark_precise: frame0: regs=r8 stack= before 2: (b7) r8 = 1024 6: R7_w=flow_keys(smin=smin32=0,smax=umax=smax32=umax32=1024,var_off =(0x0; 0x400)) R8_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1024, var_off=(0x0; 0x400)) 6: (79) r0 = *(u64 *)(r7 +0) ; R0_w=scalar() 7: (95) exit This prog loads flow_keys to r7, and adds the variable offset r8 to r7, and finally causes out-of-bounds access: BUG: unable to handle page fault for address: ffffc90014c80038 [...] Call Trace: <TASK> bpf_dispatcher_nop_func include/linux/bpf.h:1231 [inline] __bpf_prog_run include/linux/filter.h:651 [inline] bpf_prog_run include/linux/filter.h:658 [inline] bpf_prog_run_pin_on_cpu include/linux/filter.h:675 [inline] bpf_flow_dissect+0x15f/0x350 net/core/flow_dissector.c:991 bpf_prog_test_run_flow_dissector+0x39d/0x620 net/bpf/test_run.c:1359 bpf_prog_test_run kernel/bpf/syscall.c:4107 [inline] __sys_bpf+0xf8f/0x4560 kernel/bpf/syscall.c:5475 __do_sys_bpf kernel/bpf/syscall.c:5561 [inline] __se_sys_bpf kernel/bpf/syscall.c:5559 [inline] __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:5559 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Fix this by rejecting ptr alu with variable offset on flow_keys. Applying the patch rejects the program with "R7 pointer arithmetic on flow_keys prohibited".

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Restriction of Operations within the Bounds of a Memory Buffer

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerabilities (CWE-119)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerabilities

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