Linux: Use After Free
CVE-2024-40958 is a high-severity use after free 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 3a6cd326ead7c8bb1f64486789a01974a9f1ad55, 2b82028a1f5ee3a8e04090776b10c534144ae77b, cb7f811f638a14590ff98f53c6dd1fb54627d940 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 0.27% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 3a6cd326ead7c8bb1f64486789a01974a9f1ad55 or 2b82028a1f5ee3a8e04090776b10c534144ae77b or cb7f811f638a14590ff98f53c6dd1fb54627d940 or 1b631bffcb2c09551888f3c723f4365c91fe05ef, whichever matches your release line, or a later version.
- Update RUGGEDCOM RST2428P to V3.1 or a later version.
- Update SCALANCE XCM-/XRM-/XCH-/XRH-300 family to V3.1 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 0c3e0e3bb623c3735b8c9ab8aa8332f944f83a9f up to, but not including, 3a6cd326ead7c8bb1f64486789a01974a9f1ad55; 0c3e0e3bb623c3735b8c9ab8aa8332f944f83a9f up to, but not including, 2b82028a1f5ee3a8e04090776b10c534144ae77b; 0c3e0e3bb623c3735b8c9ab8aa8332f944f83a9f up to, but not including, cb7f811f638a14590ff98f53c6dd1fb54627d940; 0c3e0e3bb623c3735b8c9ab8aa8332f944f83a9f up to, but not including, 1b631bffcb2c09551888f3c723f4365c91fe05ef; 0c3e0e3bb623c3735b8c9ab8aa8332f944f83a9f up to, but not including, ef0394ca25953ea0eddcc82feae1f750451f1876; 0c3e0e3bb623c3735b8c9ab8aa8332f944f83a9f up to, but not including, 3af28df0d883e8c89a29ac31bc65f9023485743b; 0c3e0e3bb623c3735b8c9ab8aa8332f944f83a9f up to, but not including, ff960f9d3edbe08a736b5a224d91a305ccc946b0; 5.2 | 3a6cd326ead7c8bb1f64486789a01974a9f1ad55, 2b82028a1f5ee3a8e04090776b10c534144ae77b, cb7f811f638a14590ff98f53c6dd1fb54627d940, 1b631bffcb2c09551888f3c723f4365c91fe05ef, ef0394ca25953ea0eddcc82feae1f750451f1876, 3af28df0d883e8c89a29ac31bc65f9023485743b |
| Siemens | RUGGEDCOM RST2428P | before V3.1 | V3.1 |
| Siemens | SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family | Not specified in the record | Not stated |
| Siemens | SCALANCE XCM-/XRM-/XCH-/XRH-300 family | before V3.1 | V3.1 |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | before V1.1.1 | V1.1.1 |
| Linux | Linux Kernel | 5.2 up to, but not including, 5.4.279; 5.5 up to, but not including, 5.10.221; 5.11 up to, but not including, 5.15.162; 5.16 up to, but not including, 6.1.96; 6.2 up to, but not including, 6.6.36; 6.7 up to, but not including, 6.9.7; 6.10 | 5.4.279, 5.10.221, 5.15.162, 6.1.96, 6.6.36, 6.9.7 |
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 system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: netns: Make get_net_ns() handle zero refcount net Syzkaller hit a warning: refcount_t: addition on 0; use-after-free. WARNING: CPU: 3 PID: 7890 at lib/refcount.c:25 refcount_warn_saturate+0xdf/0x1d0 Modules linked in: CPU: 3 PID: 7890 Comm: tun Not tainted 6.10.0-rc3-00100-gcaa4f9578aba-dirty #310 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:refcount_warn_saturate+0xdf/0x1d0 Code: 41 49 04 31 ff 89 de e8 9f 1e cd fe 84 db 75 9c e8 76 26 cd fe c6 05 b6 41 49 04 01 90 48 c7 c7 b8 8e 25 86 e8 d2 05 b5 fe 90 <0f> 0b 90 90 e9 79 ff ff ff e8 53 26 cd fe 0f b6 1 RSP: 0018:ffff8881067b7da0 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff811c72ac RDX: ffff8881026a2140 RSI: ffffffff811c72b5 RDI: 0000000000000001 RBP: ffff8881067b7db0 R08: 0000000000000000 R09: 205b5d3730353139 R10: 0000000000000000 R11: 205d303938375420 R12: ffff8881086500c4 R13: ffff8881086500c4 R14: ffff8881086500b0 R15: ffff888108650040 FS: 00007f5b2961a4c0(0000) GS:ffff88823bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055d7ed36fd18 CR3: 00000001482f6000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? show_regs+0xa3/0xc0 ? __warn+0xa5/0x1c0 ? refcount_warn_saturate+0xdf/0x1d0 ? report_bug+0x1fc/0x2d0 ? refcount_warn_saturate+0xdf/0x1d0 ? handle_bug+0xa1/0x110 ? exc_invalid_op+0x3c/0xb0 ? asm_exc_invalid_op+0x1f/0x30 ? __warn_printk+0xcc/0x140 ? __warn_printk+0xd5/0x140 ? refcount_warn_saturate+0xdf/0x1d0 get_net_ns+0xa4/0xc0 ? __pfx_get_net_ns+0x10/0x10 open_related_ns+0x5a/0x130 __tun_chr_ioctl+0x1616/0x2370 ? __sanitizer_cov_trace_switch+0x58/0xa0 ? __sanitizer_cov_trace_const_cmp2+0x1c/0x30 ? __pfx_tun_chr_ioctl+0x10/0x10 tun_chr_ioctl+0x2f/0x40 __x64_sys_ioctl+0x11b/0x160 x64_sys_call+0x1211/0x20d0 do_syscall_64+0x9e/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5b28f165d7 Code: b3 66 90 48 8b 05 b1 48 2d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 81 48 2d 00 8 RSP: 002b:00007ffc2b59c5e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5b28f165d7 RDX: 0000000000000000 RSI: 00000000000054e3 RDI: 0000000000000003 RBP: 00007ffc2b59c650 R08: 00007f5b291ed8c0 R09: 00007f5b2961a4c0 R10: 0000000029690010 R11: 0000000000000246 R12: 0000000000400730 R13: 00007ffc2b59cf40 R14: 0000000000000000 R15: 0000000000000000 </TASK> Kernel panic - not syncing: kernel: panic_on_warn set ... This is trigger as below: ns0 ns1 tun_set_iff() //dev is tun0 tun->dev = dev //ip link set tun0 netns ns1 put_net() //ref is 0 __tun_chr_ioctl() //TUNGETDEVNETNS net = dev_net(tun->dev); open_related_ns(&net->ns, get_net_ns); //ns1 get_net_ns() get_net() //addition on 0 Use maybe_get_net() in get_net_ns in case net's ref is zero to fix this
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/1b631bffcb2c09551888f3c723f4365c91fe05ef
- git.kernel.org/stable/c/2b82028a1f5ee3a8e04090776b10c534144ae77b
- git.kernel.org/stable/c/3a6cd326ead7c8bb1f64486789a01974a9f1ad55
- git.kernel.org/stable/c/3af28df0d883e8c89a29ac31bc65f9023485743b
- git.kernel.org/stable/c/cb7f811f638a14590ff98f53c6dd1fb54627d940
- git.kernel.org/stable/c/ef0394ca25953ea0eddcc82feae1f750451f1876
- git.kernel.org/stable/c/ff960f9d3edbe08a736b5a224d91a305ccc946b0
Other references
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