CVE-2026-89780: net: qualcomm: rmnet: restore skb->dev on deaggregated frames
In the Linux kernel, the following vulnerability has been resolved:
net: qualcomm: rmnet: restore skb->dev on deaggregated frames
rmnetmapdeaggregate() allocates each sub-frame with allocskb() and leaves skb->dev NULL. rmnetmapingresshandler() assigns skb->dev = ep->egressdev only on the data path, but a MAP command frame is dispatched to rmnetmapcommand() before that, so rmnetmapsendack() runs netiftxlock(skb->dev) on a NULL device. An unprivileged user reaches this by unsharing a user+net namespace, creating an rmnet link over a tap device with INGRESSDEAGGREGATION and INGRESSMAPCOMMANDS, and writing an aggregated frame carrying a flow-control command to the tap fd.
Restore the assignment dropped by 378e25357ac7, so every skb leaving rmnetmapdeaggregate() has a valid device.
BUG: KASAN: null-ptr-deref in rawspinlock (kernel/locking/spinlock.c:158) Write of size 4 at addr 00000000000004b4 by task exploit/144 Call Trace: rawspinlock (kernel/locking/spinlock.c:158) netiftxlock (net/sched/schgeneric.c:497) rmnetmapcommand (drivers/net/ethernet/qualcomm/rmnet/rmnetmapcommand.c:67) rmnetrxhandler (drivers/net/ethernet/qualcomm/rmnet/rmnethandlers.c:125) netifreceiveskbcore.constprop.0 (net/core/dev.c:6103) ... netifreceiveskbonecore (net/core/dev.c:6214) netifreceiveskb (net/core/dev.c:6474) tungetuser (drivers/net/tun.c:1966) tunchrwriteiter (drivers/net/tun.c:2012) vfswrite (fs/readwrite.c:687) ksyswrite (fs/readwrite.c:739) dosyscall64 (arch/x86/entry/syscall64.c:94) entrySYSCALL64afterhwframe (arch/x86/entry/entry64.S:121) Kernel panic - not syncing: Fatal exception in interrupt
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.1.190-1Fixed in 6.12.115-2Fixed in 7.2.12-1Fixed in 7.2.15-1 - Upgrade
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debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.113-1~deb12u1 - Upgrade
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ubuntu/linux-aws-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1119.126~20.04.1 - Upgrade
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ubuntu/linux-azure-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1125.134~20.04.1 - Upgrade
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ubuntu/linux-azure-fde-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1124.133~20.04.1 - Upgrade
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ubuntu/linux-gcp-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1120.130~20.04.1 - Upgrade
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ubuntu/linux-hwe-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-202.212~20.04.1 - Upgrade
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ubuntu/linux-ibm-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1113.117~20.04.1 - Upgrade
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ubuntu/linux-intel-iotg-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1114.120~20.04.1 - Upgrade
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ubuntu/linux-lowlatency-hwe-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-197.207~20.04.1 - Upgrade
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ubuntu/linux-nvidia-tegra-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1070.72~20.04.1 - Upgrade
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ubuntu/linux-oracle-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1116.122~20.04.1 - Upgrade
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ubuntu/linux-riscv-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1113.117~20.04.2 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 5.15.0-202.212 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 5.15.0-1119.126 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 5.15.0-1125.134 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 5.15.0-1124.133 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 5.15.0-1120.130 - Upgrade
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ubuntu/linux-kvmto a version that resolves this vulnerability.Fixed in 5.15.0-1111.116 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 5.15.0-197.207 - Upgrade
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ubuntu/linux-nvidiato a version that resolves this vulnerability.Fixed in 5.15.0-1114.115 - Upgrade
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ubuntu/linux-nvidia-tegrato a version that resolves this vulnerability.Fixed in 5.15.0-1070.72 - Upgrade
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ubuntu/linux-nvidia-tegra-igxto a version that resolves this vulnerability.Fixed in 5.15.0-1059.59 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1119.126+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-202.212+fips1 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1
Event History
Frequently Asked Questions
What conditions must an attacker satisfy to trigger the flaw?
An unprivileged user must be able to create a user and network namespace, create an rmnet link over a tap device with INGRESS_DEAGGREGATION and INGRESS_MAP_COMMANDS enabled, and write an aggregated frame containing a flow-control command to the tap file descriptor.
What is the observable impact when exploitation succeeds?
Processing the MAP command can call netif_tx_lock() with a NULL skb->dev value, causing a NULL-pointer dereference. The reported failure is a KASAN null-pointer dereference in _raw_spin_lock during rmnet_map_command().
How can the issue be identified from crash diagnostics?
Affected crashes show a NULL-pointer dereference in _raw_spin_lock, with a call chain including netif_tx_lock(), rmnet_map_command(), and rmnet_rx_handler(). The fault is caused by a deaggregated frame reaching command handling without a valid skb->dev assignment.