Description
In the Linux kernel, the following vulnerability has been resolved: tcp: tcp_rtx_synack() can be called from process context Laurent reported the enclosed report [1] This bug triggers with following coditions: 0) Kernel built with CONFIG_DEBUG_PREEMPT=y 1) A new passive FastOpen TCP socket is created. This FO socket waits for an ACK coming from client to be a complete ESTABLISHED one. 2) A socket operation on this socket goes through lock_sock() release_sock() dance. 3) While the socket is owned by the user in step 2), a retransmit of the SYN is received and stored in socket backlog. 4) At release_sock() time, the socket backlog is processed while in process context. 5) A SYNACK packet is cooked in response of the SYN retransmit. 6) -> tcp_rtx_synack() is called in process context. Before blamed commit, tcp_rtx_synack() was always called from BH handler, from a timer handler. Fix this by using TCP_INC_STATS() & NET_INC_STATS() which do not assume caller is in non preemptible context. [1] BUG: using __this_cpu_add() in preemptible [00000000] code: epollpep/2180 caller is tcp_rtx_synack.part.0+0x36/0xc0 CPU: 10 PID: 2180 Comm: epollpep Tainted: G OE 5.16.0-0.bpo.4-amd64 #1 Debian 5.16.12-1~bpo11+1 Hardware name: Supermicro SYS-5039MC-H8TRF/X11SCD-F, BIOS 1.7 11/23/2021 Call Trace: dump_stack_lvl+0x48/0x5e check_preemption_disabled+0xde/0xe0 tcp_rtx_synack.part.0+0x36/0xc0 tcp_rtx_synack+0x8d/0xa0 ? kmem_cache_alloc+0x2e0/0x3e0 ? apparmor_file_alloc_security+0x3b/0x1f0 inet_rtx_syn_ack+0x16/0x30 tcp_check_req+0x367/0x610 tcp_rcv_state_process+0x91/0xf60 ? get_nohz_timer_target+0x18/0x1a0 ? lock_timer_base+0x61/0x80 ? preempt_count_add+0x68/0xa0 tcp_v4_do_rcv+0xbd/0x270 __release_sock+0x6d/0xb0 release_sock+0x2b/0x90 sock_setsockopt+0x138/0x1140 ? __sys_getsockname+0x7e/0xc0 ? aa_sk_perm+0x3e/0x1a0 __sys_setsockopt+0x198/0x1e0 __x64_sys_setsockopt+0x21/0x30 do_syscall_64+0x38/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae
Details
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| linux | — | 5.15.0-48.54 |
| linux-allwinner-5.19 | — | — |
| linux-aws | — | 5.15.0-1020.24 |
| linux-aws-5.0 | — | — |
| linux-aws-5.11 | — | — |
| linux-aws-5.13 | — | — |
| linux-aws-5.15 | — | 5.15.0-1020.24~20.04.1 |
| linux-aws-5.19 | — | — |
| linux-aws-5.3 | — | — |
| linux-aws-5.4 | — | 5.4.0-1085.92~18.04.1 |
| linux-aws-5.8 | — | — |
| linux-aws-6.2 | — | — |
| linux-aws-6.5 | — | — |
| linux-aws-fips | — | — |
| linux-aws-hwe | — | 4.15.0-1140.151~16.04.1 |
| linux-azure | — | 5.15.0-1020.25 |
| linux-azure-4.15 | — | 4.15.0-1150.165 |
| linux-azure-5.11 | — | — |
| linux-azure-5.13 | — | — |
| linux-azure-5.15 | — | 5.15.0-1020.25~20.04.1 |
| linux-azure-5.19 | — | — |
| linux-azure-5.3 | — | — |
| linux-azure-5.4 | — | 5.4.0-1091.96~18.04.1 |
| linux-azure-5.8 | — | — |
| linux-azure-6.2 | — | — |
| linux-azure-6.5 | — | — |
| linux-azure-edge | — | — |
| linux-azure-fde | — | — |
| linux-azure-fde-5.19 | — | — |
| linux-azure-fde-6.2 | — | — |
| linux-azure-fips | — | — |
| linux-bluefield | — | — |
| linux-fips | — | — |
| linux-gcp | — | 5.15.0-1018.24 |
| linux-gcp-4.15 | — | 4.15.0-1135.151 |
| linux-gcp-5.11 | — | — |
| linux-gcp-5.13 | — | — |
| linux-gcp-5.15 | — | 5.15.0-1018.24~20.04.1 |
| linux-gcp-5.19 | — | — |
| linux-gcp-5.3 | — | — |
| linux-gcp-5.4 | — | 5.4.0-1089.97~18.04.1 |
| linux-gcp-5.8 | — | — |
| linux-gcp-6.2 | — | — |
| linux-gcp-6.5 | — | — |
| linux-gcp-fips | — | — |
| linux-gke | — | 5.15.0-1016.19 |
| linux-gke-4.15 | — | — |
| linux-gke-5.15 | — | — |
| linux-gke-5.4 | — | — |
| linux-gkeop | — | 5.15.0-1003.5 |
| linux-gkeop-5.15 | — | — |
| linux-gkeop-5.4 | — | — |
| linux-hwe | — | — |
| linux-hwe-5.11 | — | — |
| linux-hwe-5.13 | — | — |
| linux-hwe-5.15 | — | 5.15.0-48.54~20.04.1 |
| linux-hwe-5.19 | — | — |
| linux-hwe-5.4 | — | 5.4.0-126.142~18.04.1 |
| linux-hwe-5.8 | — | — |
| linux-hwe-6.2 | — | — |
| linux-hwe-6.5 | — | — |
| linux-hwe-edge | — | — |
| linux-ibm | — | 5.15.0-1015.17 |
| linux-ibm-5.4 | — | 5.4.0-1033.37~18.04.1 |
| linux-intel-5.13 | — | — |
| linux-intel-iot-realtime | — | — |
| linux-intel-iotg | — | 5.15.0-1016.21 |
| linux-intel-iotg-5.15 | — | 5.15.0-1016.21~20.04.1 |
| linux-iot | — | 5.4.0-1004.6 |
| linux-kvm | — | 5.15.0-1018.22 |
| linux-lowlatency | — | 5.15.0-48.54 |
| linux-lowlatency-hwe-5.15 | — | 5.15.0-48.54~20.04.1 |
| linux-lowlatency-hwe-5.19 | — | — |
| linux-lowlatency-hwe-6.2 | — | — |
| linux-lowlatency-hwe-6.5 | — | — |
| linux-lts-xenial | — | — |
| linux-nvidia | — | 5.15.0-1007.7 |
| linux-nvidia-6.2 | — | — |
| linux-nvidia-6.5 | — | — |
| linux-oem | — | — |
| linux-oem-5.10 | — | — |
| linux-oem-5.13 | — | — |
| linux-oem-5.14 | — | — |
| linux-oem-5.17 | — | — |
| linux-oem-5.6 | — | — |
| linux-oem-6.0 | — | — |
| linux-oem-6.1 | — | — |
| linux-oem-6.5 | — | — |
| linux-oracle | — | 5.15.0-1018.23 |
| linux-oracle-5.0 | — | — |
| linux-oracle-5.11 | — | — |
| linux-oracle-5.13 | — | — |
| linux-oracle-5.15 | — | 5.15.0-1018.23~20.04.1 |
| linux-oracle-5.3 | — | — |
| linux-oracle-5.4 | — | 5.4.0-1083.91~18.04.1 |
| linux-oracle-5.8 | — | — |
| linux-oracle-6.5 | — | — |
| linux-raspi | — | 5.15.0-1015.17 |
| linux-raspi-5.4 | — | 5.4.0-1070.80~18.04.1 |
| linux-raspi-realtime | — | — |
| linux-raspi2 | — | — |
| linux-realtime | — | 5.15.0-1021.21 |
| linux-riscv | — | — |
| linux-riscv-5.11 | — | — |
| linux-riscv-5.15 | — | 5.15.0-1019.22~20.04.1 |
| linux-riscv-5.19 | — | — |
| linux-riscv-5.8 | — | — |
| linux-riscv-6.5 | — | — |
| linux-starfive-5.19 | — | — |
| linux-starfive-6.2 | — | — |
| linux-starfive-6.5 | — | — |
References
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