cbcvebase.
CVE-2025-68199
published 2025-12-16

CVE-2025-68199: In the Linux kernel, the following vulnerability has been resolved: codetag: debug: handle existing CODETAG_EMPTY in mark_objexts_empty for slabobj_ext When…

PriorityP420medium5.8
EPSS
0.18%
7.4th percentile
In the Linux kernel, the following vulnerability has been resolved: codetag: debug: handle existing CODETAG_EMPTY in mark_objexts_empty for slabobj_ext When alloc_slab_obj_exts() fails and then later succeeds in allocating a slab extension vector, it calls handle_failed_objexts_alloc() to mark all objects in the vector as empty. As a result all objects in this slab (slabA) will have their extensions set to CODETAG_EMPTY. Later on if this slabA is used to allocate a slabobj_ext vector for another slab (slabB), we end up with the slabB->obj_exts pointing to a slabobj_ext vector that itself has a non-NULL slabobj_ext equal to CODETAG_EMPTY. When slabB gets freed, free_slab_obj_exts() is called to free slabB->obj_exts vector. free_slab_obj_exts() calls mark_objexts_empty(slabB->obj_exts) which will generate a warning because it expects slabobj_ext vectors to have a NULL obj_ext, not CODETAG_EMPTY. Modify mark_objexts_empty() to skip the warning and setting the obj_ext value if it's already set to CODETAG_EMPTY. To quickly detect this WARN, I modified the code from WARN_ON(slab_exts[offs].ref.ct) to BUG_ON(slab_exts[offs].ref.ct == 1); We then obtained this message: [21630.898561] ------------[ cut here ]------------ [21630.898596] kernel BUG at mm/slub.c:2050! [21630.898611] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP [21630.900372] Modules linked in: squashfs isofs vfio_iommu_type1 vhost_vsock vfio vhost_net vmw_vsock_virtio_transport_common vhost tap vhost_iotlb iommufd vsock binfmt_misc nfsv3 nfs_acl nfs lockd grace netfs tls rds dns_resolver tun brd overlay ntfs3 exfat btrfs blake2b_generic xor xor_neon raid6_pq loop sctp ip6_udp_tunnel udp_tunnel nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables rfkill ip_set sunrpc vfat fat joydev sg sch_fq_codel nfnetlink virtio_gpu sr_mod cdrom drm_client_lib virtio_dma_buf drm

Affected

12 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.17.9-1 (forky)linux 6.17.9-1 (forky)
linuxlinux
linuxlinux>= 09c46563ff6d5f090211e48ff1fdba0ec7f4c97f < fc6acd4cddf76e7eb7db63649fe36980ce208f56fc6acd4cddf76e7eb7db63649fe36980ce208f56
linuxlinux>= 09c46563ff6d5f090211e48ff1fdba0ec7f4c97f < 3f56c407feb967e6faeb4e2e04eaa8edc206a6863f56c407feb967e6faeb4e2e04eaa8edc206a686
linuxlinux>= 09c46563ff6d5f090211e48ff1fdba0ec7f4c97f < 1abbdf3d57aa964e572940d67c9ec5dc877107381abbdf3d57aa964e572940d67c9ec5dc87710738
linuxlinux_kernel>= 0 < 6.12.63-16.12.63-1
linuxlinux_kernel>= 0 < 6.17.9-16.17.9-1
linuxlinux_kernel>= 0 < 6.17.0-14.146.17.0-14.14
linuxlinux_kernel>= 6.10.0 < 6.12.596.12.59
linuxlinux_kernel>= 6.13.0 < 6.17.96.17.9
ubuntulinux-aws
ubuntulinux-oracle
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