CVE: CVE-2024-46755
Published: 2024-09-18
Description: 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 <ctrl-c> and starting it again this happens:

| Unable to handle kernel NULL pointer dereference at virtual address [PII_REDACTED]
| Mem abort info:
|   ESR = 0x[PII_REDACTED]000004
|   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=[PII_REDACTED]d96000
| [[PII_REDACTED]] pgd=[PII_REDACTED], p4d=[PII_REDACTED]
| Internal error: Oops: [PII_REDACTED] [#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: [PII_REDACTED]
| x26:[PII_REDACTED]00002c x25: [PII_REDACTED] x24:[PII_REDACTED]e86bc9
| x23: ffff000006bfd996 x22: [PII_REDACTED] x21: ffff000007bec000
| x20:[PII_REDACTED]00002c x19: [PII_REDACTED] x18: [PII_REDACTED]
| x17:[PII_REDACTED]44ffff x16: 00500072b5503510 x15: ccc283740681e517
| x14:[PII_REDACTED]006d15 x13:[PII_REDACTED]e8ff43 x12: 002c01000000ffb1
| x11: [PII_REDACTED] x10: 02e8ff43002c0100 x9 : 0000ffb100100157
| x8 : ffff000003d20000 x7 :[PII_REDACTED]0002f1 x6 : 00000000ffffe124
| x5 : [PII_REDACTED] x4 : [PII_REDACTED] x3 : [PII_REDACTED]
| x2 : [PII_REDACTED] x1 : [PII_REDACTED] x0 : [PII_REDACTED]
| 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 [PII_REDACTED] ]---
CVSS Score: 5.5 (MEDIUM)
CWE: CWE-476
References: https://git.kernel.org/stable/c/1a05d8d02cfa3540ea5dbd6b39446bd3f515521f; https://git.kernel.org/stable/c/9813770f25855b866b8ead8155b8806b2db70f6d; https://git.kernel.org/stable/c/a12cf97cbefa139ef8d95081f2ea047cbbd74b7a