Bug 1980069 (CVE-2021-35039) - CVE-2021-35039 kernel: allows loading unsigned kernel modules via init_module syscall
Summary: CVE-2021-35039 kernel: allows loading unsigned kernel modules via init_module...
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2021-35039
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1980070 1980433
Blocks: 1980071
TreeView+ depends on / blocked
 
Reported: 2021-07-07 17:17 UTC by Guilherme de Almeida Suckevicz
Modified: 2022-04-17 21:29 UTC (History)
43 users (show)

Fixed In Version: Linux kernel 5.13
Doc Type: If docs needed, set a value
Doc Text:
A flaw incorrect handle of boot param module.sig_enforce=1 in the Linux kernel modules sign verification functionality was found in the way user boot with this param enabled and both if kernel compiled with param CONFIG_MODULE_SIG unset, then user still can load unsigned module even param module.sig_enforce pretending to be enabled. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
Clone Of:
Environment:
Last Closed: 2021-08-03 15:49:09 UTC
Embargoed:

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Description Guilherme de Almeida Suckevicz 2021-07-07 17:17:36 UTC 
kernel/module.c in the Linux kernel before 5.12.14 mishandles Signature Verification. Without CONFIG_MODULE_SIG, verification that a kernel module is signed, for loading via init_module, does not occur for a module.sig_enforce=1 command-line argument.

Reference:
https://www.openwall.com/lists/oss-security/2021/07/06/3

Upstream patch:
https://github.com/torvalds/linux/commit/0c18f29aae7ce3dadd26d8ee3505d07cc982df75
Comment 1 Guilherme de Almeida Suckevicz 2021-07-07 17:18:06 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1980070]
Comment 2 Justin M. Forbes 2021-07-08 13:59:33 UTC 
Fedora enables MODULE_SIG so should not be vulnerable to this, The patch is included in the stable update 5.12.14 for Fedora, so users building their own configs should be covered there as well.
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