Bug 2212513 (CVE-2023-3111)

Summary:	CVE-2023-3111 kernel: Use after free in prepare_to_relocate in fs/btrfs/relocation.c
Product:	[Other] Security Response	Reporter:	Rohit Keshri <rkeshri>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	acaringi, allarkin, bhu, chwhite, crwood, dbohanno, ddepaula, debarbos, dfreiber, dvlasenk, ezulian, hkrzesin, jarod, jburrell, jdenham, jfaracco, jferlan, jforbes, jlelli, joe.lawrence, jshortt, jstancek, jwyatt, kcarcia, kernel-mgr, ldoskova, lgoncalv, lleshchi, lzampier, nmurray, ptalbert, qzhao, rogbas, rrobaina, rvrbovsk, rysulliv, scweaver, tyberry, vkumar, walters, wcosta, williams, wmealing, ycote
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	Kernel 6.0-rc2	Doc Type:	If docs needed, set a value
Doc Text:	A use-after-free flaw was found in prepare_to_relocate in fs/btrfs/relocation.c in btrfs in the Linux Kernel. This issue can be triggered by calling btrfs_ioctl_balance() before calling btrfs_ioctl_defrag().	Story Points:	---
Clone Of:		Environment:
Last Closed:	2023-06-06 00:32:12 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2212347

Description Rohit Keshri 2023-06-05 18:51:17 UTC

In btrfs_relocate_block_group(), the structure variable rc is allocated. Then btrfs_relocate_block_group() calls relocate_block_group() -> prepare_to_relocate() -> set_reloc_control(), and assigns rc to the variable fs_info->reloc_ctl. 

When prepare_to_relocate() returns, it calls btrfs_commit_transaction() -> btrfs_start_dirty_block_groups() -> btrfs_alloc_path() -> kmem_cache_zalloc(), which may fail. When the failure occurs, btrfs_relocate_block_group() detects the error and frees rc and doesn't set fs_info->reloc_ctl to NULL. After that, in btrfs_init_reloc_root(), rc is retrieved from fs_info->reloc_ctl and then used, which may cause
a use-after-free bug.

This possible bug can be triggered by calling btrfs_ioctl_balance() before calling btrfs_ioctl_defrag().

Refer:
https://patchwork.kernel.org/project/linux-btrfs/patch/20220721074829.2905233-1-r33s3n6@gmail.com/

Comment 3 Product Security DevOps Team 2023-06-06 00:32:08 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2023-3111