Bug 1879671 (CVE-2020-25085)

Summary: CVE-2020-25085 QEMU: sdhci: out-of-bounds access issue while doing multi block SDMA
Product: [Other] Security Response Reporter: Prasad Pandit <ppandit>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: ailan, berrange, cfergeau, dbecker, drjones, imammedo, itamar, jen, jferlan, jforbes, jjoyce, jmaloy, jschluet, knoel, lhh, lpeer, m.a.young, mburns, mkenneth, mrezanin, mst, ondrejj, pbonzini, philmd, ribarry, rjones, robinlee.sysu, sclewis, slinaber, virt-maint, virt-maint, vkuznets, xen-maint
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in QEMU. An out-of-bounds read/write access issue was found in the SDHCI Controller emulator of QEMU. It may occur while doing multi block SDMA, if transfer block size exceeds the 's->fifo_buffer[s->buf_maxsz]' size which would leave the current element pointer 's->data_count' pointing out of bounds. This would lead the subsequent DMA r/w operation to an OOB access issue where a guest user/process may use this flaw to crash the QEMU process resulting in DoS scenario. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
 Story Points: ---
Clone Of: Environment:
Last Closed: 2020-09-16 20:41:05 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1879673, 1910678    
Bug Blocks: 1850259    

Description Prasad Pandit 2020-09-16 18:49:01 UTC 
An out-of-bounds r/w access issue was found in the SDHCI Controller emulator of QEMU. It may occur while doing multi block SDMA, if transfer block size exceeds the 's->fifo_buffer[s->buf_maxsz]' size. It'd leave the current element pointer 's->data_count' pointing out of bounds. Leading the subsequent DMA r/w operation to OOB access issue. A guest user/process may use this flaw to crash the QEMU process resulting in DoS scenario.

Upstream patches:
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  -> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg00733.html
  -> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg01439.html

Reference:
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  -> https://www.openwall.com/lists/oss-security/2020/09/16/6
Comment 1 Prasad Pandit 2020-09-16 18:49:10 UTC 
Acknowledgments:

Name: Sergej Schumilo (Ruhr-University Bochum), Cornelius Aschermann (Ruhr-University Bochum), Simon Wrner (Ruhr-University Bochum)
Comment 2 Prasad Pandit 2020-09-16 18:49:15 UTC 
External References:

https://bugs.launchpad.net/qemu/+bug/1892960
https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Fsdhci_oob_write1
Comment 3 Prasad Pandit 2020-09-16 18:49:44 UTC 
Created qemu tracking bugs for this issue:

Affects: fedora-all [bug 1879673]
Comment 4 Product Security DevOps Team 2020-09-16 20:41:05 UTC 
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2020-25085