Bug 2265833 (CVE-2024-26603)

Summary: CVE-2024-26603 kernel: x86/fpu: Stop relying on userspace for info to fault in xsave buffer that cause loop forever
Product: [Other] Security Response Reporter: Mauro Matteo Cascella <mcascell>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: acaringi, allarkin, aquini, bhu, chwhite, cye, cyin, dbohanno, debarbos, dfreiber, drow, dvlasenk, esandeen, ezulian, hkrzesin, jarod, jburrell, jdenham, jfaracco, jforbes, jlelli, joe.lawrence, jshortt, jstancek, jwyatt, kcarcia, kyoshida, ldoskova, lgoncalv, lzampier, mleitner, mmilgram, mstowell, nmurray, ptalbert, rparrazo, rrobaina, rvrbovsk, rysulliv, scweaver, sukulkar, tglozar, tyberry, vkumar, wcosta, williams, wmealing, ycote, ykopkova, zhijwang
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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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Last Closed: Type: ---
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Documentation: --- CRM:
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 2265834    
Bug Blocks: 2267044    

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]

Comment 6 errata-xmlrpc 2024-06-05 00:30:27 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2024:3618 https://access.redhat.com/errata/RHSA-2024:3618

Comment 7 errata-xmlrpc 2024-06-05 10:01:14 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2024:3627 https://access.redhat.com/errata/RHSA-2024:3627

Comment 8 Alex 2024-06-09 17:03:34 UTC
The result of automatic check (that is developed by Alexander Larkin) for this CVE-2024-26603 is: CHECK	Maybe valid. Check manually. with impact LOW (that is an approximation based on flags  ; these flags parsed automatically based on patch data). Such automatic check happens only for Low/Moderates (and only when not from reporter, but parsing already existing CVE). Highs always checked manually (I check it myself and then we check it again in Remediation team). In rare cases some of the Moderates could be increased to High later.