Bug 1696604 (CVE-2018-20449) - CVE-2018-20449 kernel: reading "callback=" lines in a debugfs file in drivers/dma/qcom/hidma_dbg.c results in information disclosure
Summary: CVE-2018-20449 kernel: reading "callback=" lines in a debugfs file in drivers...
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2018-20449
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: 1696605
Blocks: Embargoed1696607
TreeView+ depends on / blocked
 
Reported: 2019-04-05 08:41 UTC by Marian Rehak
Modified: 2021-02-16 22:08 UTC (History)
43 users (show)

Fixed In Version:
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Doc Text:
The hidma_chan_stats() function in the drivers/dma/qcom/hidma_dbg.c file in the Linux kernel allows local users to obtain sensitive address information by reading "callback=" lines in a debugfs file. By default, the debugfs filesystem access is restricted so only a privileged user can access it.
Clone Of:
Environment:
Last Closed: 2019-04-12 11:31:34 UTC

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Description Marian Rehak 2019-04-05 08:41:48 UTC 
The hidma_chan_stats() function in the drivers/dma/qcom/hidma_dbg.c file in the Linux kernel allows local users to obtain sensitive address information by reading "callback=" lines in a debugfs file. By default debugfs filesystem access is restricted, so only a privileged user can access it.

References:

https://www.mail-archive.com/debian-security-tracker@lists.debian.org/msg03808.html 

Upstream patches:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ad67b74d2469d9b82aaa572d76474c95bc484d57

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=91efafb1dd8f471177a3dddb4841d75d3df1cc46
Comment 1 Marian Rehak 2019-04-05 08:42:24 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1696605]
Comment 3 Justin M. Forbes 2019-04-11 19:57:06 UTC 
This was mitigated in 4.15 and newer kernels with commit ad67b74d2469d9b82aaa572d76474c95bc484d57 "printk: hash addresses printed with %p"
Comment 6 Vladis Dronov 2019-04-12 11:31:34 UTC 
Note:

RHEL-8 has the %p cloaking patchset integrated, so %p is cloaked if printed. RHEL-ALT is vulnerable to this flaw, but by default debugfs filesystem access is restricted, so only a privileged user (a real "root") can access it. Henceforth, we do not believe this issue is a security flaw. Earlier RHEL versions do not build and ship the code in question.
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