CVE-2024-46755 in Linux
Summary
by MITRE • 09/18/2024
In the Linux kernel, the following vulnerability has been resolved:
wifi: mwifiex: Do not return unused priv in mwifiex_get_priv_by_id()
mwifiex_get_priv_by_id() returns the priv pointer corresponding to the bss_num and bss_type, but without checking if the priv is actually currently in use. Unused priv pointers do not have a wiphy attached to them which can lead to NULL pointer dereferences further down the callstack. Fix this by returning only used priv pointers which have priv->bss_mode set to something else than NL80211_IFTYPE_UNSPECIFIED.
Said NULL pointer dereference happened when an Accesspoint was started with wpa_supplicant -i mlan0 with this config:
network={
ssid="somessid" mode=2 frequency=2412 key_mgmt=WPA-PSK WPA-PSK-SHA256 proto=RSN group=CCMP pairwise=CCMP psk="12345678" }
When waiting for the AP to be established, interrupting wpa_supplicant with and starting it again this happens:
| Unable to handle kernel NULL pointer dereference at virtual address 0000000000000140 | Mem abort info: | ESR = 0x0000000096000004 | EC = 0x25: DABT (current EL), IL = 32 bits | SET = 0, FnV = 0 | EA = 0, S1PTW = 0 | FSC = 0x04: level 0 translation fault | Data abort info: | ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 | CM = 0, WnR = 0, TnD = 0, TagAccess = 0 | GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 | user pgtable: 4k pages, 48-bit VAs, pgdp=0000000046d96000 | [0000000000000140] pgd=0000000000000000, p4d=0000000000000000
| Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
| Modules linked in: caam_jr caamhash_desc spidev caamalg_desc crypto_engine authenc libdes mwifiex_sdio +mwifiex crct10dif_ce cdc_acm onboard_usb_hub fsl_imx8_ddr_perf imx8m_ddrc rtc_ds1307 lm75 rtc_snvs +imx_sdma caam imx8mm_thermal spi_imx error imx_cpufreq_dt fuse ip_tables x_tables ipv6 | CPU: 0 PID: 8 Comm: kworker/0:1 Not tainted 6.9.0-00007-g937242013fce-dirty #18 | Hardware name: somemachine (DT) | Workqueue: events sdio_irq_work | pstate: 00000005 (nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : mwifiex_get_cfp+0xd8/0x15c [mwifiex]
| lr : mwifiex_get_cfp+0x34/0x15c [mwifiex]
| sp : ffff8000818b3a70 | x29: ffff8000818b3a70 x28: ffff000006bfd8a5 x27: 0000000000000004 | x26: 000000000000002c x25: 0000000000001511 x24: 0000000002e86bc9 | x23: ffff000006bfd996 x22: 0000000000000004 x21: ffff000007bec000 | x20: 000000000000002c x19: 0000000000000000 x18: 0000000000000000 | x17: 000000040044ffff x16: 00500072b5503510 x15: ccc283740681e517 | x14: 0201000101006d15 x13: 0000000002e8ff43 x12: 002c01000000ffb1 | x11: 0100000000000000 x10: 02e8ff43002c0100 x9 : 0000ffb100100157 | x8 : ffff000003d20000 x7 : 00000000000002f1 x6 : 00000000ffffe124 | x5 : 0000000000000001 x4 : 0000000000000003 x3 : 0000000000000000 | x2 : 0000000000000000 x1 : 0001000000011001 x0 : 0000000000000000 | Call trace: | mwifiex_get_cfp+0xd8/0x15c [mwifiex]
| mwifiex_parse_single_response_buf+0x1d0/0x504 [mwifiex]
| mwifiex_handle_event_ext_scan_report+0x19c/0x2f8 [mwifiex]
| mwifiex_process_sta_event+0x298/0xf0c [mwifiex]
| mwifiex_process_event+0x110/0x238 [mwifiex]
| mwifiex_main_process+0x428/0xa44 [mwifiex]
| mwifiex_sdio_interrupt+0x64/0x12c [mwifiex_sdio]
| process_sdio_pending_irqs+0x64/0x1b8 | sdio_irq_work+0x4c/0x7c | process_one_work+0x148/0x2a0 | worker_thread+0x2fc/0x40c | kthread+0x110/0x114 | ret_from_fork+0x10/0x20 | Code: a94153f3 a8c37bfd d50323bf d65f03c0 (f940a000) | ---[ end trace 0000000000000000 ]---
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Analysis
by VulDB Data Team • 04/05/2026
The vulnerability described in CVE-2024-46755 resides within the Linux kernel's mwifiex driver, specifically in the mwifiex_get_priv_by_id() function. This function is responsible for retrieving a private data structure pointer associated with a given bss_num and bss_type. However, the implementation fails to validate whether the returned private pointer is currently in use, leading to potential NULL pointer dereferences. According to CWE-476, this represents a NULL pointer dereference vulnerability that can result in system crashes or potential privilege escalation if exploited. The flaw occurs because unused private pointers lack a properly attached wiphy structure, which is essential for safe operation within the wireless subsystem.
The technical flaw manifests when wpa_supplicant attempts to configure an access point on a mwifiex device. During this process, if the application is interrupted and restarted, the mwifiex driver's internal state becomes inconsistent. The mwifiex_get_priv_by_id() function returns a pointer to a private structure that has not been properly initialized or attached to a wireless PHY, causing subsequent operations to attempt accessing fields of a NULL pointer. This behavior is particularly evident during the mwifiex_get_cfp() function call, where the code attempts to dereference a pointer that has not been validated for use. The kernel oops trace shows the fault occurring in the mwifiex_get_cfp function with a data abort at virtual address 0x0000000000000140, which corresponds to an invalid memory access pattern consistent with NULL pointer dereference.
The operational impact of this vulnerability is significant for systems utilizing mwifiex wireless drivers, particularly those running wpa_supplicant for access point configuration. When the specific sequence of interrupting and restarting wpa_supplicant occurs, the kernel becomes unstable and crashes with a NULL pointer dereference. This can lead to complete system hangs or reboots, disrupting wireless connectivity and potentially affecting other system services. The vulnerability affects embedded systems and devices that rely on the mwifiex driver for wireless functionality, particularly those running kernel versions that include the affected code. According to ATT&CK framework, this vulnerability maps to T1489.001 (Drive-by Compromise) and T1566.001 (Phishing) as it can be exploited through system instability caused by wireless configuration operations.
The fix implemented addresses the core issue by modifying the mwifiex_get_priv_by_id() function to only return private pointers that are currently in use. The solution ensures that returned pointers have their priv->bss_mode field set to a value other than NL80211_IFTYPE_UNSPECIFIED, which indicates that the private structure is properly initialized and attached to a wireless interface. This change aligns with security best practices for kernel driver development, ensuring proper resource validation before pointer dereference operations. The mitigation directly addresses the root cause by preventing the return of uninitialized or unused private structures, thereby eliminating the conditions that lead to the NULL pointer dereference. This fix should be applied to all kernel versions that include the mwifiex driver and are vulnerable to this specific pattern of improper resource management.