🛡️ UBUNTU-CVE-2020-36789
⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

In the Linux kernel, the following vulnerability has been resolved: can: dev: can_get_echo_skb(): prevent call to kfree_skb() in hard IRQ context If a driver calls can_get_echo_skb() during a hardware IRQ (which is often, but not always, the case), the 'WARN_ON(in_irq)' in net/core/skbuff.c#skb_release_head_state() might be triggered, under network congestion circumstances, together with the potential risk of a NULL pointer dereference. The root cause of this issue is the call to kfree_skb() instead of dev_kfree_skb_irq() in net/core/dev.c#enqueue_to_backlog(). This patch prevents the skb to be freed within the call to netif_rx() by incrementing its reference count with skb_get(). The skb is finally freed by one of the in-irq-context safe functions: dev_consume_skb_any() or dev_kfree_skb_any(). The "any" version is used because some drivers might call can_get_echo_skb() in a normal context. The reason for this issue to occur is that initially, in the core network stack, loopback skb were not supposed to be received in hardware IRQ context. The CAN stack is an exeption. This bug was previously reported back in 2017 in [1] but the proposed patch never got accepted. While [1] directly modifies net/core/dev.c, we try to propose here a smoother modification local to CAN network stack (the assumption behind is that only CAN devices are affected by this issue). [1] http://lore.kernel.org/r/[email protected]

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2025-04-17
Updated 2026-06-15
Modified 2026-06-03
Fix URL N/A

Affected Packages

Software From version Fixed in
linux 5.4.0-59.65
linux-allwinner-5.19
linux-aws 5.4.0-1034.35
linux-aws-5.0
linux-aws-5.11
linux-aws-5.13
linux-aws-5.19
linux-aws-5.3
linux-aws-5.4 5.4.0-1034.35~18.04.1
linux-aws-5.8
linux-aws-6.2
linux-aws-6.5
linux-aws-fips
linux-aws-hwe 4.15.0-1093.99~16.04.1
linux-azure 5.4.0-1035.36
linux-azure-4.15 4.15.0-1106.118
linux-azure-5.11
linux-azure-5.13
linux-azure-5.19
linux-azure-5.3
linux-azure-5.4 5.4.0-1035.36~18.04.1
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 5.4.0-1033.35
linux-gcp-4.15 4.15.0-1092.105
linux-gcp-5.11
linux-gcp-5.13
linux-gcp-5.19
linux-gcp-5.3
linux-gcp-5.4 5.4.0-1033.35~18.04.1
linux-gcp-5.8
linux-gcp-6.2
linux-gcp-6.5
linux-gcp-fips
linux-gke
linux-gke-4.15
linux-gke-5.15
linux-gke-5.4
linux-gkeop
linux-gkeop-5.15
linux-gkeop-5.4
linux-hwe
linux-hwe-5.11
linux-hwe-5.13
linux-hwe-5.19
linux-hwe-5.4 5.4.0-59.65~18.04.1
linux-hwe-5.8
linux-hwe-6.2
linux-hwe-6.5
linux-hwe-edge
linux-intel-5.13
linux-intel-iot-realtime
linux-kvm 5.4.0-1031.32
linux-lowlatency-hwe-5.19
linux-lowlatency-hwe-6.2
linux-lowlatency-hwe-6.5
linux-lts-xenial 4.4.0-198.230~14.04.1
linux-nvidia
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 5.4.0-1034.36
linux-oracle-5.0
linux-oracle-5.11
linux-oracle-5.13
linux-oracle-5.3
linux-oracle-5.4 5.4.0-1034.36~18.04.1
linux-oracle-5.8
linux-oracle-6.5
linux-raspi 5.4.0-1026.29
linux-raspi-5.4 5.4.0-1026.29~18.04.1
linux-raspi-realtime
linux-raspi2
linux-realtime
linux-riscv
linux-riscv-5.11
linux-riscv-5.19
linux-riscv-5.8
linux-riscv-6.5
linux-starfive-5.19
linux-starfive-6.2
linux-starfive-6.5

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