Bug 1540439 (CVE-2018-1000028) - CVE-2018-1000028 kernel: Improper sorting of GIDs in nfsd can lead to incorrect permissions being applied
Summary: CVE-2018-1000028 kernel: Improper sorting of GIDs in nfsd can lead to incorre...
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2018-1000028
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
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Depends On: Red Hat1516978 Engineering1540442
Blocks: Embargoed1856325
TreeView+ depends on / blocked
 
Reported: 2018-01-31 04:58 UTC by Sam Fowler
Modified: 2020-07-24 14:59 UTC (History)
49 users (show)

Fixed In Version: kernel 4.15
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Last Closed: 2020-07-24 14:59:44 UTC

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Description Sam Fowler 2018-01-31 04:58:01 UTC 
nfsd in the Linux kernel 4.15, does not properly sort gids when rootsquash is enabled. The groups_sort() function is called inside a loop that copies/squashes gids. he net result is that the highest numbered valid gids are replaced with any lower-valued garbage gids, possibly including 0.

This can corrupt group membership, leading to permission denials for the client.

Upstream Patch:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1995266727fa8143897e89b55f5d3c79aa828420
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