CVE-2026-98503
- Source
- https://cve.org/CVERecord?id=CVE-2026-98503
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98503.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-98503
- Downstream
- Published
- 2026-10-18T15:17:03Z
- Modified
- 2026-10-19T02:46:30Z
- Summary
- packet: use ubuf_info completion for TX_RING packets
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
packet: use ubuf_info completion for TX_RING packets
tpacket_snd sends skbs with frags pointing into its ring slots. Slots are released when skb->destructor is called.
A call to skb_orphan calls skb->destructor before the skb is freed. This can cause the slot to be reused while still linked into the skb.
Switch to standard zerocopy completion (ubuf_info) so the slot is only released once all references to the payload are freed or copied. Restore skb->destructor to standard sock_wfree.
The ubuf_info completion callback can be called with a NULL skb, but only from net_zcopy_put and related API, used by zerocopy implementations that hold their own reference on the uarg, such as MSG_ZEROCOPY. This uarg is only ever completed from skb_zcopy_clear, so skb is always set.
To prevent userspace from aliasing in-flight state on shared ring slots, allocate tpacket_uarg per packet, rather than per slot. This adds a small allocation to the transmit path. Use standard kmalloc to allow backporting to stable kernels.
The uarg holds an sk_wmem_alloc reference, rather than an sk_refcnt reference. packet_free_tx_ring waits on sk_wmem_alloc before freeing the ring pages. Always allocate vec->deferred for tx_ring so page-backed rings also wait on sk_wmem_alloc when skb_copy_ubufs drops page refs before calling tpacket_ubuf_complete.
Drop the tx_ring.pg_vec test that tpacket_destruct_skb performed before accessing the slot. The sk_wmem_alloc reference now guarantees that the slot is valid. The test is also not sufficient by itself, as it reads pg_vec without pg_vec_lock, so it can race with packet_set_ring.
As a result a slot is released when its payload is copied, which can be before transmission (e.g., in skb_orphan_frags_rx). If copied before skb_tx_timestamp() is called, no slot timestamp is recorded, similar to when skb_orphan() was called early in the datapath before this patch.
Revert the now unused previous skb_zcopy_.._nouarg infra.
Depends on commit 992cc9f94ca9 ("net/packet: defer vmalloc TX_RING free until skbs finish").
- Database specific
{ "cna_assigner": "Linux", "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98503.json" }- References
-
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- https://git.kernel.org/stable/c/2a0c9afefc0ecea2cc30ccfbbbc98182a0986191
- https://git.kernel.org/stable/c/9518405613863d0bf0700927a21367f5942cf058
- https://git.kernel.org/stable/c/e67c455d79fbf709a94965f09a2be6bf4f4ba5fd
- https://git.kernel.org/stable/c/eda9bcb721f15a93746a99eabda33d80b86404fd
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98503.json
- https://nvd.nist.gov/vuln/detail/CVE-2026-98503
Affected packages
Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected ranges
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced5cd8d46ea1562be80063f53c7c6a5f40224de623Fixede67c455d79fbf709a94965f09a2be6bf4f4ba5fdFixededa9bcb721f15a93746a99eabda33d80b86404fdFixed2a0c9afefc0ecea2cc30ccfbbbc98182a0986191Fixed9518405613863d0bf0700927a21367f5942cf058
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced4.14.86Fixed4.15
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced4.19.7Fixed4.20
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced67f6fba765ef8cb19089d476e3c367212a2fbdfd
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introducedf2a67e68dbaeae7c88e5522873d7b908911f9f77