{"id":"CVE-2026-80852","title":"tls: device: fix out-of-bounds write in tls_append_frag()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ntls: device: fix out-of-bounds write in tls_append_frag()\n\nFound with syzkaller and a local syzbot instance running on top of a\nnetdevsim TLS offload emulation; tls_dev…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < 03ced5da6120965d80ed56dbb7d78fa5c9128906","Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < a832d7cb09da2a8e4e9734b4be14d3e76169d805","Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < b7f10d4ff987bda038df90052cd4a1434a7412d4","Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < fadbc1ed2a872a8649a44cf9e1cf9621fc58cd6e","Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < cd7e875b89597f3498917af764758391338d1802","Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < 7e1208c135618358da5d7d6664874dc6e53c62fc","Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < b17cf742eaad70ae29ac558cefb3aa9bbeea03d4","Linux 4.18"],"published":"2026-09-04","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:44:46.363Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-80852","references":[{"url":"https://git.kernel.org/stable/c/03ced5da6120965d80ed56dbb7d78fa5c9128906"},{"url":"https://git.kernel.org/stable/c/a832d7cb09da2a8e4e9734b4be14d3e76169d805"},{"url":"https://git.kernel.org/stable/c/b7f10d4ff987bda038df90052cd4a1434a7412d4"},{"url":"https://git.kernel.org/stable/c/fadbc1ed2a872a8649a44cf9e1cf9621fc58cd6e"},{"url":"https://git.kernel.org/stable/c/cd7e875b89597f3498917af764758391338d1802"},{"url":"https://git.kernel.org/stable/c/7e1208c135618358da5d7d6664874dc6e53c62fc"},{"url":"https://git.kernel.org/stable/c/b17cf742eaad70ae29ac558cefb3aa9bbeea03d4"}],"tags":["cve.org"],"epss":0.00161,"epssPercentile":0.0486,"ingestedAt":"2026-10-19T09:16:01.495Z","slug":"CVE-2026-80852","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ntls: device: fix out-of-bounds write in tls_append_frag()\n\nFound with syzkaller and a local syzbot instance running on top of a\nnetdevsim TLS offload emulation; tls_device.c is otherwise only reachable\non a machine with a NIC that implements the offload.\n\ntls_push_data() only checks whether the open record still has room for\nanother frag at the bottom of its loop, and the MSG_MORE early break\nskips that check.  The record survives to the next syscall with the frag\ncount it already had, and tls_append_frag() does not check either, so\nwith TLS_TX_ZEROCOPY_RO every splice(SPLICE_F_MORE) of a byte or two adds\na non-coalescing pipe page and num_frags walks off the end of\ntls_record_info.frags[MAX_SKB_FRAGS].  Once the record is pushed,\ntls_push_record() runs the same index over sg_tx_data[MAX_SKB_FRAGS] and\nthe sg_set_page() writes land on the destruct_work that follows it, which\nthe workqueue then calls.\n\nThe byte limit is fine because copy drops to 0 and the loop falls through\nto the same check; the frag count has no such feedback.\n\nPush the record rather than keep a full one open, which is what a plain\nTCP socket does - tcp_sendmsg_locked() uses tcp_mark_push() and\nnew_segment in both the copy and the MSG_SPLICE_PAGES paths, and tls_sw\nalready sets full_record when the sk_msg ring fills up, MSG_MORE or not.\n\n  BUG: KASAN: slab-out-of-bounds in tls_append_frag ( net/tls/tls_device.c:269)\n  Write of size 8 at addr ffff8881104d1530 by task tls_oob/450\n\n  CPU: 2 UID: 0 PID: 450 Comm: tls_oob Not tainted 7.2.0-rc7+ #329 PREEMPT\n  Call Trace:\n   <TASK>\n   dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)\n   print_report (mm/kasan/report.c:378 mm/kasan/report.c:482)\n   kasan_report (mm/kasan/report.c:595)\n   tls_append_frag (net/tls/tls_device.c:269)\n   tls_push_data (net/tls/tls_device.c:518)\n   tls_device_sendmsg (net/tls/tls_device.c:583)\n   inet_sendmsg (net/ipv4/af_inet.c:865)\n   sock_sendmsg (net/socket.c:775 net/socket.c:790 net/socket.c:813)\n   splice_to_socket (fs/splice.c:884)\n   do_splice (fs/splice.c:936 fs/splice.c:1349)\n   __do_splice (fs/splice.c:1431)\n   __x64_sys_splice (fs/splice.c:1634 fs/splice.c:1616)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)\n   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n   </TASK>\n\nand, once the record is pushed:\n\n  UBSAN: array-index-out-of-bounds in net/tls/tls_device.c:300:24\n  index 18 is out of range for type 'skb_frag_t [17]'\n  UBSAN: array-index-out-of-bounds in net/tls/tls_device.c:301:41\n  index 18 is out of range for type 'scatterlist [17]'\n  UBSAN: array-index-out-of-bounds in net/tls/tls_device.c:302:39\n  index 18 is out of range for type 'scatterlist [17]'\n  UBSAN: array-index-out-of-bounds in net/tls/tls_device.c:307:38\n  index 26 is out of range for type 'scatterlist [17]'\n\n  kernel tried to execute NX-protected page - exploit attempt? (uid: 0)\n  BUG: unable to handle page fault for address: ffffea000411a680\n  #PF: supervisor instruction fetch in kernel mode\n  #PF: error_code(0x0011) - permissions violation\n  Oops: Oops: 0011 [#1] SMP KASAN PTI\n  Workqueue: ktls_device_destruct 0xffffea000411a680\n  RIP: 0010:0xffffea000411a680\n  Call Trace:\n   <TASK>\n   worker_thread (kernel/workqueue.c:3405 kernel/workqueue.c:3486)\n   kthread (kernel/kthread.c:436)\n   ret_from_fork (arch/x86/kernel/process.c:158)\n   ret_from_fork_asm (arch/x86/entry/entry_64.S:245)\n   </TASK>\n\n## Affected\n\n- `Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < 03ced5da6120965d80ed56dbb7d78fa5c9128906`\n- `Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < a832d7cb09da2a8e4e9734b4be14d3e76169d805`\n- `Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < b7f10d4ff987bda038df90052cd4a1434a7412d4`\n- `Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < fadbc1ed2a872a8649a44cf9e1cf9621fc58cd6e`\n- `Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < cd7e875b89597f3498917af764758391338d1802`\n- `Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < 7e1208c135618358da5d7d6664874dc6e53c62fc`\n- `Linux >= e8f69799810c32dd40c6724d829eccc70baad07f < b17cf742eaad70ae29ac558cefb3aa9bbeea03d4`\n- `Linux 4.18`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}