Linux Kernel up to 7.3-rc3 skfp skfp_ctl_set_mac_address null pointer dereference

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4.2	$0-$5k	0.00

Summaryinfo

A vulnerability categorized as problematic has been discovered in Linux Kernel up to 7.3-rc3. The impacted element is the function skfp_ctl_set_mac_address of the component skfp. Executing a manipulation can lead to null pointer dereference. This vulnerability appears as CVE-2026-98302. The attack requires local access. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 7.3-rc3 and classified as problematic. This vulnerability affects the function skfp_ctl_set_mac_address of the component skfp. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: net: fddi: skfp: fix NULL deref when setting the MAC address while down skfp_ctl_set_mac_address() calls ResetAdapter() unconditionally, without checking netif_running(). ResetAdapter() first calls card_stop(), which sets smc->hw.hw_state to STOPPED, and then mac_drv_clear_tx_queue(), which walks the two transmit queues: for (i = QUEUE_S; i <= QUEUE_A0; i++) { queue = smc->hw.fp.tx[i] ; ... t = queue->tx_curr_get ; smc->hw.fp.tx[] is only populated by init_tx(), which is reached from skfp_open() through init_smt() -> init_fddi_driver() -> init_fplus() -> init_mac() -> init_tx(). The private area is allocated and zeroed by alloc_fddidev(), so on an interface that has never been brought up both queue pointers are still NULL. The hw_state test at the top of mac_drv_clear_tx_queue() does not catch this, because card_stop() has just set STOPPED; the function proceeds into the loop and dereferences NULL. ResetAdapter() does call init_smt() itself, but only after the queues have been cleared. Setting the MAC address on a down interface therefore oopses: ip link set dev fddi0 address 02:00:00:00:00:01 BUG: KASAN: null-ptr-deref in mac_drv_clear_tx_queue+0x68/0x2c0 [skfp] Read of size 8 at addr 0000000000000010 by task ip/302 Call Trace: <TASK> mac_drv_clear_tx_queue+0x68/0x2c0 [skfp 6c01d4bab63c36978bd0a7d7e90837adb44cc37b] ResetAdapter+0x29/0x100 [skfp 6c01d4bab63c36978bd0a7d7e90837adb44cc37b] skfp_ctl_set_mac_address+0x57/0x80 [skfp 6c01d4bab63c36978bd0a7d7e90837adb44cc37b] netif_set_mac_address+0x1e4/0x2c0 do_setlink+0x684/0x2680 </TASK> Address 0x10 is the offset of tx_curr_get, the third pointer in struct s_smt_tx_queue, on 64-bit. mac_drv_clear_rx_queue(), which ResetAdapter() calls immediately afterwards, dereferences smc->hw.fp.rx[QUEUE_R1] in the same way behind the same ineffective hw_state test; the transmit queue merely crashes first. Both are covered by the guard below. Skip the adapter reset when the interface is down. dev_addr_set() is left unconditional, so the new address is still recorded in dev->dev_addr. Nothing is lost by not resetting the adapter here: skfp_open() deliberately re-reads the factory address on every open, read_address(smc, NULL); eth_hw_addr_set(dev, smc->hw.fddi_canon_addr.a); and the comment above it states this is done to discard exactly such an address override across a close/open cycle. An address set while the interface is down could not have survived the following open even before this change, so the guard removes no working behaviour. Guarding the hardware side of ndo_set_mac_address() with netif_running() is established practice; skge_set_mac_address() has done so since commit 2eb3e621c4e0 ("skge: set mac address bonding fix"). Guarding the reset as a whole, rather than NULL-checking the queues, is also what the rest of the driver expects. After a previous open/close the queue pointers are stale but non-NULL, so there is no crash, yet ResetAdapter() goes on to call smt_online() and STI_FBI() ("Enable Board Interrupts") while skfp_close() has already called free_irq() - the adapter would be brought back online with no handler installed. The only other ResetAdapter() caller is skfp_interrupt(), which by construction runs only while the device is open. Found by automated driver testing against an emulated SysKonnect FDDI adapter under a KASAN-enabled 7.0.0 kernel. Triggering it requires CAP_NET_ADMIN.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2026-98302 since 09/25/2026. The exploitation appears to be easy. Local access is required to approach this attack. Additional levels of successful authentication are necessary for exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.54, 7.2.8 or 7.3-rc4 eliminates this vulnerability. Applying the patch 835903bea770ad96ab4322e18d98e00f8e0b39c3/5fd0f401b3eee95c93daa35ef99cb03d676031f0/731db6110b3148331ed8d5d11a564bfd520721d9/822903ed991971780db1db1be31a4f00e2b13e30/616ba18b2cfb72b7bea214bdd72df2485b2e37dc/d6f63fdb298d546a47790cb373db65462c264d04/438131e7ae847e907d345bf504d7e25585561b5c/7c8810c2e69c3d9ca6df870b40ae9218e50b4fb1 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.10.270
• 5.15.221
• 6.1.188
• 6.6.157
• 6.12.111
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 6.18.40
• 6.18.41
• 6.18.42
• 6.18.43
• 6.18.44
• 6.18.45
• 6.18.46
• 6.18.47
• 6.18.48
• 6.18.49
• 6.18.50
• 6.18.51
• 6.18.52
• 6.18.53
• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5
• 7.2.6
• 7.2.7
• 7.3-rc1
• 7.3-rc2
• 7.3-rc3

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.4
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.4
VulDB Temp Score: 4.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
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Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.271/5.15.222/6.1.189/6.6.158/6.12.112/6.18.54/7.2.8/7.3-rc4
Patch: 835903bea770ad96ab4322e18d98e00f8e0b39c3/5fd0f401b3eee95c93daa35ef99cb03d676031f0/731db6110b3148331ed8d5d11a564bfd520721d9/822903ed991971780db1db1be31a4f00e2b13e30/616ba18b2cfb72b7bea214bdd72df2485b2e37dc/d6f63fdb298d546a47790cb373db65462c264d04/438131e7ae847e907d345bf504d7e25585561b5c/7c8810c2e69c3d9ca6df870b40ae9218e50b4fb1

Timelineinfo

09/25/2026 CVE reserved
10/06/2026 +11 days Advisory disclosed
10/06/2026 +0 days VulDB entry created
10/06/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CNA: Linux
CVE: CVE-2026-98302 (🔒)

GCVE (CVE): GCVE-0-2026-98302
GCVE (VulDB): GCVE-100-414058

Entryinfo

Created: 10/06/2026 12:25
Changes: 10/06/2026 12:25 (59)
Complete: 🔍
Cache ID: 216::103

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Discussion

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