Bug 2265833 (CVE-2024-26603) - CVE-2024-26603 kernel: x86/fpu: Stop relying on userspace for info to fault in xsave buffer that cause loop forever
Summary: CVE-2024-26603 kernel: x86/fpu: Stop relying on userspace for info to fault i...
Status: NEW
Alias: CVE-2024-26603
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Product Security
QA Contact:
Depends On: 2265834
Blocks: 2267044
TreeView+ depends on / blocked
Reported: 2024-02-24 17:40 UTC by Mauro Matteo Cascella
Modified: 2024-05-15 11:46 UTC (History)
49 users (show)

Fixed In Version: kernel 6.1.79, kernel 6.6.18, kernel 6.7.6, kernel 6.8-rc4
Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the Linux kernel's x86/fpu module, which revolves around an issue with relying on user space for critical information regarding the xsave buffer. In the affected scenario, the expected size of the user space buffer is derived from user-controlled data, specifically, fx_sw->xstate_size. By manipulating this value, an attacker could construct a malicious sigreturn frame where the indicated size is smaller than required by valid bits in fx_sw->xfeatures. Furthermore, the attacker could unmap portions of the fpu buffer in the user space, rendering them inaccessible to xrstor. This manipulation leads to a situation where xrstor repeatedly attempts to restore and access an unmapped area, causing a fault. However, the fault_in_readable function erroneously succeeds because the accessed region, buf + fx_sw->xstate_size, remains within the mapped area. Consequently, the system enters a perpetual loop as xrstor continually retries the operation.
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Description Mauro Matteo Cascella 2024-02-24 17:40:33 UTC
In the Linux kernel, the following vulnerability has been resolved:

x86/fpu: Stop relying on userspace for info to fault in xsave buffer

The Linux kernel CVE team has assigned CVE-2024-26603 to this issue.

Upstream advisory:

Comment 1 Mauro Matteo Cascella 2024-02-24 17:41:01 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 2265834]

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