wifi: mwifiex: fix NULL dereference when the AP has HT-cap but no HT-oper

Overview

In the Linux kernel, the following vulnerability has been resolved:

wifi: mwifiex: fix NULL dereference when the AP has HT-cap but no HT-oper

mwifiex_tdls_add_ht_oper() gates its follow-the-AP-bandwidth path on bss_desc->bcn_ht_cap being present, but then dereferences a different pointer, bss_desc->bcn_ht_oper:

if (ISSUPP_CHANWIDTH40(priv->adapter->hw_dot_11n_dev_cap) &&
    bss_desc->bcn_ht_cap &&
    ISALLOWED_CHANWIDTH40(bss_desc->bcn_ht_oper->ht_param))

bcn_ht_cap and bcn_ht_oper are populated independently while parsing the associated AP's beacon in mwifiex_update_bss_desc_with_ie(): an AP that advertises an HT Capabilities element but no HT Operation element leaves bcn_ht_cap non-NULL and bcn_ht_oper NULL. Setting up a TDLS link to a peer while associated to such an AP then dereferences the NULL bcn_ht_oper and crashes the kernel. Every other bcn_ht_oper user in the driver NULL-checks it first.

Guard on the pointer that is actually dereferenced.

Found by 0sec automated security-research tooling (https://0sec.ai).

Affected

• Linux >= 396939f94084d5923d558e9f22db48bc51156e47 < e1770f7410b4232a0267924f99751dc9c5ca31af
• Linux >= 396939f94084d5923d558e9f22db48bc51156e47 < 8c2058717fd06f05d421c2d3adf1dff3c3abcda1
• Linux >= 396939f94084d5923d558e9f22db48bc51156e47 < fba7eb7b248ea0618235f504158b685d752a153a
• Linux >= 396939f94084d5923d558e9f22db48bc51156e47 < eb42c3c8fd479166c42984728754cd779c71fd60
• Linux >= 396939f94084d5923d558e9f22db48bc51156e47 < 45011e4d9ba3f2182e5df64be65888044fa20771
• Linux >= 396939f94084d5923d558e9f22db48bc51156e47 < 9375a4ea4121625ef27a46b74781cda66a5cc61b
• Linux >= 396939f94084d5923d558e9f22db48bc51156e47 < cca4398aa305c22016d1714f388e2fa6ea4e5ad4
• Linux >= 396939f94084d5923d558e9f22db48bc51156e47 < c3d68e294cbb6a4090bb219d3dcaca85a011809b
• Linux 3.16

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.