Bug 1959585 (CVE-2021-3548) - CVE-2021-3548 dmg2img: OOB in dmg2img.c memcpy() causing undefined behavior
Summary: CVE-2021-3548 dmg2img: OOB in dmg2img.c memcpy() causing undefined behavior
Keywords:
Status: CLOSED UPSTREAM
Alias: CVE-2021-3548
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1959587
Blocks: 1955789 1959678
TreeView+ depends on / blocked
 
Reported: 2021-05-11 20:15 UTC by Cedric Buissart
Modified: 2021-05-26 18:35 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in dmg2img through 20170502. dmg2img did not validate the size of the read buffer during memcpy() inside the main() function. 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.
Clone Of:
Environment:
Last Closed: 2021-05-13 02:33:47 UTC


Attachments (Terms of Use)

Description Cedric Buissart 2021-05-11 20:15:09 UTC
dmg2img did not validate the size of the read buffer during memcpy() inside the main() function. 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.

The vulnerability appears at the following code :

```
memcpy(parts[i].Data, base64data + 0xCC, parts[i].BlocksRunCount * 0x28);
```


An attacker could request a specially crafted DMG image to be converted by the dmg2img command. The attacker has the ability to control the size of the memcpy(), via `parts[i].BlocksRunCount` thus forcing an OOB read, and memory information to be written in the parts[i].Data allocation, or possibly crashing the command.


Upstream bug report :
https://github.com/Lekensteyn/dmg2img/issues/9

Comment 1 Cedric Buissart 2021-05-11 20:15:36 UTC
Created dmg2img tracking bugs for this issue:

Affects: fedora-all [bug 1959587]

Comment 2 Cedric Buissart 2021-05-11 20:15:53 UTC
Acknowledgments:

Name: Anshunkang Zhou

Comment 4 Product Security DevOps Team 2021-05-13 02:33:47 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.


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