| From bippy-7c5fe7eed585 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2025-21925: llc: do not use skb_get() before dev_queue_xmit() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| llc: do not use skb_get() before dev_queue_xmit() |
| |
| syzbot is able to crash hosts [1], using llc and devices |
| not supporting IFF_TX_SKB_SHARING. |
| |
| In this case, e1000 driver calls eth_skb_pad(), while |
| the skb is shared. |
| |
| Simply replace skb_get() by skb_clone() in net/llc/llc_s_ac.c |
| |
| Note that e1000 driver might have an issue with pktgen, |
| because it does not clear IFF_TX_SKB_SHARING, this is an |
| orthogonal change. |
| |
| We need to audit other skb_get() uses in net/llc. |
| |
| [1] |
| |
| kernel BUG at net/core/skbuff.c:2178 ! |
| Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI |
| CPU: 0 UID: 0 PID: 16371 Comm: syz.2.2764 Not tainted 6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0 |
| Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 |
| RIP: 0010:pskb_expand_head+0x6ce/0x1240 net/core/skbuff.c:2178 |
| Call Trace: |
| <TASK> |
| __skb_pad+0x18a/0x610 net/core/skbuff.c:2466 |
| __skb_put_padto include/linux/skbuff.h:3843 [inline] |
| skb_put_padto include/linux/skbuff.h:3862 [inline] |
| eth_skb_pad include/linux/etherdevice.h:656 [inline] |
| e1000_xmit_frame+0x2d99/0x5800 drivers/net/ethernet/intel/e1000/e1000_main.c:3128 |
| __netdev_start_xmit include/linux/netdevice.h:5151 [inline] |
| netdev_start_xmit include/linux/netdevice.h:5160 [inline] |
| xmit_one net/core/dev.c:3806 [inline] |
| dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3822 |
| sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343 |
| __dev_xmit_skb net/core/dev.c:4045 [inline] |
| __dev_queue_xmit+0x13d4/0x43e0 net/core/dev.c:4621 |
| dev_queue_xmit include/linux/netdevice.h:3313 [inline] |
| llc_sap_action_send_test_c+0x268/0x320 net/llc/llc_s_ac.c:144 |
| llc_exec_sap_trans_actions net/llc/llc_sap.c:153 [inline] |
| llc_sap_next_state net/llc/llc_sap.c:182 [inline] |
| llc_sap_state_process+0x239/0x510 net/llc/llc_sap.c:209 |
| llc_ui_sendmsg+0xd0d/0x14e0 net/llc/af_llc.c:993 |
| sock_sendmsg_nosec net/socket.c:718 [inline] |
| |
| The Linux kernel CVE team has assigned CVE-2025-21925 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.4.291 with commit cd1c44327bbbd50fc24f2b38892f5f328b784d0f |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.10.235 with commit 13f3f872627f0f27c31245524fc11367756240ad |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.15.179 with commit 9b6f083db141ece0024be01526aa05aa978811cb |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.1.131 with commit 17f86e25431ebc15aa9245ff156414fdad47822d |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.6.83 with commit 416e8b4c20c6398044e93008deefd563289f477d |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.12.19 with commit 0f764208dc24ea043c3e20194d32aebf94f8459c |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.13.7 with commit 056e8a46d79e22983bae4267e0d9c52927076f46 |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.14 with commit 64e6a754d33d31aa844b3ee66fb93ac84ca1565e |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2025-21925 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| net/llc/llc_s_ac.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/cd1c44327bbbd50fc24f2b38892f5f328b784d0f |
| https://git.kernel.org/stable/c/13f3f872627f0f27c31245524fc11367756240ad |
| https://git.kernel.org/stable/c/9b6f083db141ece0024be01526aa05aa978811cb |
| https://git.kernel.org/stable/c/17f86e25431ebc15aa9245ff156414fdad47822d |
| https://git.kernel.org/stable/c/416e8b4c20c6398044e93008deefd563289f477d |
| https://git.kernel.org/stable/c/0f764208dc24ea043c3e20194d32aebf94f8459c |
| https://git.kernel.org/stable/c/056e8a46d79e22983bae4267e0d9c52927076f46 |
| https://git.kernel.org/stable/c/64e6a754d33d31aa844b3ee66fb93ac84ca1565e |
