Bug 1959911 (CVE-2021-32614)

Summary: CVE-2021-32614 dmg2img: OOB read in memcpy() for up to 204 bytes in fill_mishblk()
Product: [Other] Security Response Reporter: Cedric Buissart <cbuissar>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED UPSTREAM QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: lemenkov, lkundrak
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in dmg2img through 20170502. fill_mishblk() does not check the length of the read buffer, and copy 0xCC bytes from it. The length of the buffer is controlled by an attacker. By providing a length smaller than 0xCC, memcpy reaches out of the malloc'ed bound. This possibly leads to memory layout information leaking in the data. This might be used in a chain of vulnerability in order to reach code execution.
Story Points: ---
Clone Of: Environment:
Last Closed: 2021-05-13 14:33:52 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 1959912    
Bug Blocks: 1955789, 1959943    

Description Cedric Buissart 2021-05-12 15:32:55 UTC
fill_mishblk() does not check the length of the read buffer, and copy 0xCC bytes from it. The length of the buffer is controlled by an attacker. By providing a length smaller than 0xCC, memcpy reaches out of the malloc'ed bound.
This possibly leads to memory layout information leaking in the data. This might be used in a chain of vulnerability in order to reach code execution.

```
185 void fill_mishblk(char* c, struct _mishblk* m)
186 {
187     memset(m, 0, sizeof(struct _mishblk));
188     memcpy(m, c, 0xCC);
```
In the above code, the memory allocated for `c` may be shorter than 0xCC bytes.

Upstream bug report :
https://github.com/Lekensteyn/dmg2img/issues/11

Comment 1 Cedric Buissart 2021-05-12 15:33:14 UTC
Created dmg2img tracking bugs for this issue:

Affects: fedora-all [bug 1959912]

Comment 2 Cedric Buissart 2021-05-12 15:35:31 UTC
Acknowledgments:

Name: Anshunkang Zhou

Comment 4 Product Security DevOps Team 2021-05-13 14:33:52 UTC
This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.