CVE-2025-38033
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-06-18

Last updated on: 2025-11-14

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: x86/Kconfig: make CFI_AUTO_DEFAULT depend on !RUST or Rust >= 1.88 Calling core::fmt::write() from rust code while FineIBT is enabled results in a kernel panic: [ 4614.199779] kernel BUG at arch/x86/kernel/cet.c:132! [ 4614.205343] Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI [ 4614.211781] CPU: 2 UID: 0 PID: 6057 Comm: dmabuf_dump Tainted: G U O 6.12.17-android16-0-g6ab38c534a43 #1 9da040f27673ec3945e23b998a0f8bd64c846599 [ 4614.227832] Tainted: [U]=USER, [O]=OOT_MODULE [ 4614.241247] RIP: 0010:do_kernel_cp_fault+0xea/0xf0 ... [ 4614.398144] RIP: 0010:_RNvXs5_NtNtNtCs3o2tGsuHyou_4core3fmt3num3impyNtB9_7Display3fmt+0x0/0x20 [ 4614.407792] Code: 48 f7 df 48 0f 48 f9 48 89 f2 89 c6 5d e9 18 fd ff ff 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 41 81 ea 14 61 af 2c 74 03 0f 0b 90 <66> 0f 1f 00 55 48 89 e5 48 89 f2 48 8b 3f be 01 00 00 00 5d e9 e7 [ 4614.428775] RSP: 0018:ffffb95acfa4ba68 EFLAGS: 00010246 [ 4614.434609] RAX: 0000000000000000 RBX: 0000000000000010 RCX: 0000000000000000 [ 4614.442587] RDX: 0000000000000007 RSI: ffffb95acfa4ba70 RDI: ffffb95acfa4bc88 [ 4614.450557] RBP: ffffb95acfa4bae0 R08: ffff0a00ffffff05 R09: 0000000000000070 [ 4614.458527] R10: 0000000000000000 R11: ffffffffab67eaf0 R12: ffffb95acfa4bcc8 [ 4614.466493] R13: ffffffffac5d50f0 R14: 0000000000000000 R15: 0000000000000000 [ 4614.474473] ? __cfi__RNvXs5_NtNtNtCs3o2tGsuHyou_4core3fmt3num3impyNtB9_7Display3fmt+0x10/0x10 [ 4614.484118] ? _RNvNtCs3o2tGsuHyou_4core3fmt5write+0x1d2/0x250 This happens because core::fmt::write() calls core::fmt::rt::Argument::fmt(), which currently has CFI disabled: library/core/src/fmt/rt.rs: 171 // FIXME: Transmuting formatter in new and indirectly branching to/calling 172 // it here is an explicit CFI violation. 173 #[allow(inline_no_sanitize)] 174 #[no_sanitize(cfi, kcfi)] 175 #[inline] 176 pub(super) unsafe fn fmt(&self, f: &mut Formatter<'_>) -> Result { This causes a Control Protection exception, because FineIBT has sealed off the original function's endbr64. This makes rust currently incompatible with FineIBT. Add a Kconfig dependency that prevents FineIBT from getting turned on by default if rust is enabled. [ Rust 1.88.0 (scheduled for 2025-06-26) should have this fixed [1], and thus we relaxed the condition with Rust >= 1.88. When `objtool` lands checking for this with e.g. [2], the plan is to ideally run that in upstream Rust's CI to prevent regressions early [3], since we do not control `core`'s source code. Alice tested the Rust PR backported to an older compiler. Peter would like that Rust provides a stable `core` which can be pulled into the kernel: "Relying on that much out of tree code is 'unfortunate'". - Miguel ] [ Reduced splat. - Miguel ]
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Meta Information
Published
2025-06-18
Last Modified
2025-11-14
Generated
2026-05-07
AI Q&A
2025-06-18
EPSS Evaluated
2026-05-05
NVD
CVE-2025-38033
Affected Vendors & Products
Showing 7 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel 6.15
linux linux_kernel 6.15
linux linux_kernel 6.15
linux linux_kernel 6.15
linux linux_kernel 6.15
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
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CWE ID Description
CWE-NVD-CWE-noinfo
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability occurs in the Linux kernel when Rust code calls core::fmt::write() while FineIBT (a control flow integrity feature) is enabled. The call leads to a kernel panic due to a Control Flow Integrity (CFI) violation. Specifically, core::fmt::write() calls core::fmt::rt::Argument::fmt(), which currently has CFI disabled, causing a Control Protection exception because FineIBT expects certain control flow protections that are not met. This incompatibility causes the kernel to crash (kernel panic). The issue is addressed by making FineIBT disabled by default when Rust is enabled, and it is expected to be fixed in Rust version 1.88 or later.


How can this vulnerability impact me? :

This vulnerability can cause the Linux kernel to panic (crash) when Rust code that uses core::fmt::write() is executed with FineIBT enabled. A kernel panic results in system instability and potential downtime, which can disrupt services and operations relying on the affected kernel. It may also complicate debugging and system reliability until the issue is resolved by updating Rust or kernel configurations.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by observing kernel panic logs related to FineIBT enabled systems running Rust code that calls core::fmt::write(). Look for kernel BUG messages in dmesg or journalctl logs similar to: '[ 4614.199779] kernel BUG at arch/x86/kernel/cet.c:132!' and 'Oops: invalid opcode: 0000'. You can use commands like 'dmesg | grep -i "kernel BUG"' or 'journalctl -k | grep -i "kernel BUG"' to detect these panic messages.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation involves disabling FineIBT when using Rust code in the kernel or ensuring that the Rust compiler version is 1.88 or higher, as the fix is included starting from Rust 1.88. Additionally, the kernel configuration should be adjusted so that CFI_AUTO_DEFAULT depends on !RUST or Rust >= 1.88, preventing FineIBT from being enabled by default when Rust is enabled.


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