CVE-2026-99193 in Linux
Summary
by MITRE • 10/28/2026
In the Linux kernel, the following vulnerability has been resolved:
net: ti: icssm-prueth: Move setting of netops to fix crash
icssm_prueth_netdev_init() calls of_phy_get_and_connect() before ndev->netdev_ops is assigned. phy_attach_direct() -> phy_link_topo_add_phy() reads dev->netdev_ops through netdev_need_ops_lock() since the commit in question, so probing crashes with a NULL pointer dereference when CONFIG_NET_SHAPER is enabled.
Assign netdev_ops before the PHY attach, as was done for emac in commit 7c9f391ec89c ("net: emac: move setting of netops to fix crash").
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Analysis
by VulDB Data Team • 10/28/2026
The vulnerability identified within the Linux kernel involves a critical initialization sequence error in the TI ICSSM PRU-ETH network driver, specifically affecting systems where CONFIG_NET_SHAPER is enabled. This issue manifests as a NULL pointer dereference during device probing, which can lead to system instability or a complete crash of the kernel module responsible for handling network operations on these specific hardware interfaces. The root cause lies in the ordering of function calls within the icssm_prueth_netdev_init routine, where the driver attempts to interact with PHY layer components before fully initializing its own net device structure.
The technical flaw originates from a change introduced by commit 7c9f391ec89c which modified how network devices handle operations locks via the netdev_need_ops_lock function. This modification caused phy_attach_direct, specifically through the internal call to phy_link_topo_add_phy, to attempt reading the dev->netdev_ops pointer while it was still uninitialized or null. In C programming terms, accessing a member of a structure that has not been properly allocated or assigned results in undefined behavior, typically manifesting as a segmentation fault when the kernel attempts to dereference a NULL address. This race condition between driver initialization and PHY attachment exposes a classic software defect where state assumptions are violated during early boot stages.
From a classification perspective, this vulnerability aligns with CWE-476, which denotes a NULL Pointer Dereference. It also relates to CWE-362 regarding Race Conditions involving shared resources if the timing of initialization is considered in concurrent contexts, although here it is primarily an ordering issue within a single thread during probe execution. The impact on ATT&CK techniques would fall under initial access vectors where system instability could be leveraged for denial-of-service scenarios or potentially exploited to gain control over kernel memory if the NULL dereference leads to unexpected code paths, though in this specific case, it is primarily a stability issue rather than an arbitrary write primitive.
The operational impact of this vulnerability is significant for users deploying TI ICSSM PRU-ETH based hardware with network shaper capabilities enabled. During system boot or module loading, the kernel will crash immediately upon attempting to probe these devices, rendering the network interface unusable and potentially taking down the entire host if not handled by a watchdog or panic-on-crash configuration. This disrupts connectivity for any services relying on this specific NIC type and requires manual intervention such as disabling CONFIG_NET_SHAPER or applying the patch to restore functionality.
Mitigation strategies involve updating the Linux kernel to include the fix that reorders the initialization sequence. Specifically, developers must ensure that ndev->netdev_ops is assigned before calling of_phy_get_and_connect(). This mirrors a previous correction applied to the emac driver in commit 7c9f391ec89c and establishes a consistent pattern for network drivers interacting with PHY layers. System administrators should apply kernel updates promptly or disable CONFIG_NET_SHAPER if immediate patching is not feasible, although disabling this feature may impact traffic shaping capabilities required by their specific deployment architecture.