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In the Linux kernel, the following vulnerability has been resolved:
btrfs: zoned: fix use-after-free in do_zone_finish()
Shinichiro reported the following use-after-free triggered by the device replace operation in fstests btrfs/070.
BTRFS info (device nullb1): scrub: finished on devid 1 with status: 0 ================================================================== BUG: KASAN: slab-use-after-free in do_zone_finish+0x91a/0xb90 [btrfs] Read of size 8 at addr ffff8881543c8060 by task btrfs-cleaner/3494007
CPU: 0 PID: 3494007 Comm: btrfs-cleaner Tainted: G W 6.8.0-rc5-kts #1 Hardware name: Supermicro Super Server/X11SPi-TF, BIOS 3.3 02/21/2020 Call Trace: <TASK> dump_stack_lvl+0x5b/0x90 print_report+0xcf/0x670 ? __virt_addr_valid+0x200/0x3e0 kasan_report+0xd8/0x110 ? do_zone_finish+0x91a/0xb90 [btrfs] ? do_zone_finish+0x91a/0xb90 [btrfs] do_zone_finish+0x91a/0xb90 [btrfs] btrfs_delete_unused_bgs+0x5e1/0x1750 [btrfs] ? __pfx_btrfs_delete_unused_bgs+0x10/0x10 [btrfs] ? btrfs_put_root+0x2d/0x220 [btrfs] ? btrfs_clean_one_deleted_snapshot+0x299/0x430 [btrfs] cleaner_kthread+0x21e/0x380 [btrfs] ? __pfx_cleaner_kthread+0x10/0x10 [btrfs] kthread+0x2e3/0x3c0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x31/0x70 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 </TASK>
Allocated by task 3493983: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 btrfs_alloc_device+0xb3/0x4e0 [btrfs] device_list_add.constprop.0+0x993/0x1630 [btrfs] btrfs_scan_one_device+0x219/0x3d0 [btrfs] btrfs_control_ioctl+0x26e/0x310 [btrfs] __x64_sys_ioctl+0x134/0x1b0 do_syscall_64+0x99/0x190 entry_SYSCALL_64_after_hwframe+0x6e/0x76
Freed by task 3494056: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3f/0x60 poison_slab_object+0x102/0x170 __kasan_slab_free+0x32/0x70 kfree+0x11b/0x320 btrfs_rm_dev_replace_free_srcdev+0xca/0x280 [btrfs] btrfs_dev_replace_finishing+0xd7e/0x14f0 [btrfs] btrfs_dev_replace_by_ioctl+0x1286/0x25a0 [btrfs] btrfs_ioctl+0xb27/0x57d0 [btrfs] __x64_sys_ioctl+0x134/0x1b0 do_syscall_64+0x99/0x190 entry_SYSCALL_64_after_hwframe+0x6e/0x76
The buggy address belongs to the object at ffff8881543c8000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 96 bytes inside of freed 1024-byte region [ffff8881543c8000, ffff8881543c8400)
The buggy address belongs to the physical page: page:00000000fe2c1285 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1543c8 head:00000000fe2c1285 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x17ffffc0000840(slab|head|node=0|zone=2|lastcpupid=0x1fffff) page_type: 0xffffffff() raw: 0017ffffc0000840 ffff888100042dc0 ffffea0019e8f200 dead000000000002 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8881543c7f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8881543c7f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8881543c8000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881543c8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881543c8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
This UAF happens because we're accessing stale zone information of a already removed btrfs_device in do_zone_finish().
The sequence of events is as follows:
btrfs_dev_replace_start btrfs_scrub_dev btrfs_dev_replace_finishing btrfs_dev_replace_update_device_in_mapping_tree <-- devices replaced btrfs_rm_dev_replace_free_srcdev btrfs_free_device <-- device freed
cleaner_kthread btrfs_delete_unused_bgs btrfs_zone_finish do_zone_finish <-- refers the freed device
The reason for this is that we're using a ---truncated---
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Debian | — | Upgrade linux | May 15, 2025 | May 1, 2024 |
| Suse | — | Upgrade kernel-64kb-extraUpgrade kernel-docsUpgrade kernel-rt_debugUpgrade reiserfs-kmp-azureUpgrade kselftests-kmp-azureUpgrade reiserfs-kmp-64kbUpgrade dtb-alteraUpgrade reiserfs-kmp-defaultUpgrade dtb-nvidiaUpgrade kernel-rt_debug-develUpgrade kernel-azure-optionalUpgrade kernel-default-base-rebuildUpgrade kernel-obs-buildUpgrade kernel-debug-develUpgrade dtb-caviumUpgrade dtb-broadcomUpgrade gfs2-kmp-defaultUpgrade kernel-default-optionalUpgrade kselftests-kmp-rtUpgrade kernel-azureUpgrade dlm-kmp-rtUpgrade kernel-debug-vdsoUpgrade kernel-docs-htmlUpgrade dlm-kmp-defaultUpgrade cluster-md-kmp-rtUpgrade ocfs2-kmp-64kbUpgrade kernel-default-livepatch-develUpgrade kernel-defaultUpgrade kernel-source-vanillaUpgrade ocfs2-kmp-defaultUpgrade kernel-source-rtUpgrade dtb-renesasUpgrade dtb-rockchipUpgrade kernel-rt-vdsoUpgrade kernel-rt_debug-livepatch-develUpgrade kernel-kvmsmall-vdsoUpgrade gfs2-kmp-azureUpgrade ocfs2-kmp-azureUpgrade kernel-rt-optionalUpgrade dtb-xilinxUpgrade dtb-amdUpgrade kernel-rt-extraUpgrade dtb-socionextUpgrade reiserfs-kmp-rtUpgrade cluster-md-kmp-64kbUpgrade dtb-sprdUpgrade kernel-develUpgrade dtb-allwinnerUpgrade kernel-default-baseUpgrade kernel-default-livepatchUpgrade kernel-devel-azureUpgrade kernel-64kb-livepatch-develUpgrade dtb-qcomUpgrade dtb-amazonUpgrade dtb-mediatekUpgrade kernel-macrosUpgrade dtb-lgUpgrade kernel-64kb-optionalUpgrade cluster-md-kmp-defaultUpgrade kernel-syms-rtUpgrade kernel-obs-qaUpgrade kernel-default-extraUpgrade cluster-md-kmp-azureUpgrade gfs2-kmp-rtUpgrade gfs2-kmp-64kbUpgrade dlm-kmp-azureUpgrade kernel-source-azureUpgrade kernel-rt-develUpgrade kernel-kvmsmall-develUpgrade kernel-64kbUpgrade kernel-azure-develUpgrade kernel-zfcpdumpUpgrade dtb-armUpgrade dtb-appleUpgrade dtb-amlogicUpgrade dlm-kmp-64kbUpgrade dtb-exynosUpgrade ocfs2-kmp-rtUpgrade kernel-syms-azureUpgrade dtb-freescaleUpgrade kernel-64kb-develUpgrade kernel-kvmsmallUpgrade kselftests-kmp-defaultUpgrade kernel-symsUpgrade kernel-rt_debug-vdsoUpgrade kernel-rt-livepatch-develUpgrade kernel-devel-rtUpgrade kernel-default-vdsoUpgrade kernel-azure-extraUpgrade dtb-marvellUpgrade dtb-apmUpgrade kernel-rtUpgrade kernel-default-develUpgrade kernel-sourceUpgrade dtb-hisiliconUpgrade kernel-azure-vdsoUpgrade kernel-azure-livepatch-develUpgrade kernel-debug-livepatch-develUpgrade kernel-kvmsmall-livepatch-develUpgrade kselftests-kmp-64kbUpgrade kernel-debug | Aug 8, 2024 | May 1, 2024 |
| Ubuntu | — | Upgrade linux-image-6.8.0-1009-awsUpgrade linux-image-generic-hwe-24.04Upgrade linux-image-awsUpgrade linux-image-gkeUpgrade linux-image-kvmUpgrade linux-image-6.8.0-1004-gkeUpgrade linux-image-virtualUpgrade linux-image-virtual-hwe-24.04Upgrade linux-image-oracleUpgrade linux-image-oem-24.04Upgrade linux-image-6.8.0-1008-azure-fdeUpgrade linux-image-6.8.0-35-lowlatencyUpgrade linux-image-generic-64k-hwe-24.04Upgrade linux-image-6.8.0-35-genericUpgrade linux-image-6.8.0-35-lowlatency-64kUpgrade linux-image-6.8.0-1008-gcpUpgrade linux-image-6.8.0-1006-oemUpgrade linux-image-6.8.0-35-generic-64kUpgrade linux-image-ibmUpgrade linux-image-ibm-lts-24.04Upgrade linux-image-lowlatency-64kUpgrade linux-image-oracle-64kUpgrade linux-image-ibm-classicUpgrade linux-image-generic-lpaeUpgrade linux-image-6.8.0-1006-oracleUpgrade linux-image-6.8.0-1006-oracle-64kUpgrade linux-image-6.8.0-1008-azureUpgrade linux-image-oem-24.04aUpgrade linux-image-lowlatencyUpgrade linux-image-azure-fdeUpgrade linux-image-gcpUpgrade linux-image-raspiUpgrade linux-image-6.8.0-1006-ibmUpgrade linux-image-genericUpgrade linux-image-generic-64kUpgrade linux-image-6.8.0-1005-raspiUpgrade linux-image-azure | Jul 1, 2024 | May 1, 2024 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Oct 17, 2025 | May 1, 2024 |
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