• Li Zetao's avatar
    wifi: rtlwifi: Fix global-out-of-bounds bug in _rtl8812ae_phy_set_txpower_limit() · 117dbeda
    Li Zetao authored
    There is a global-out-of-bounds reported by KASAN:
    
      BUG: KASAN: global-out-of-bounds in
      _rtl8812ae_eq_n_byte.part.0+0x3d/0x84 [rtl8821ae]
      Read of size 1 at addr ffffffffa0773c43 by task NetworkManager/411
    
      CPU: 6 PID: 411 Comm: NetworkManager Tainted: G      D
      6.1.0-rc8+ #144 e15588508517267d37
      Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
      Call Trace:
       <TASK>
       ...
       kasan_report+0xbb/0x1c0
       _rtl8812ae_eq_n_byte.part.0+0x3d/0x84 [rtl8821ae]
       rtl8821ae_phy_bb_config.cold+0x346/0x641 [rtl8821ae]
       rtl8821ae_hw_init+0x1f5e/0x79b0 [rtl8821ae]
       ...
       </TASK>
    
    The root cause of the problem is that the comparison order of
    "prate_section" in _rtl8812ae_phy_set_txpower_limit() is wrong. The
    _rtl8812ae_eq_n_byte() is used to compare the first n bytes of the two
    strings from tail to head, which causes the problem. In the
    _rtl8812ae_phy_set_txpower_limit(), it was originally intended to meet
    this requirement by carefully designing the comparison order.
    For example, "pregulation" and "pbandwidth" are compared in order of
    length from small to large, first is 3 and last is 4. However, the
    comparison order of "prate_section" dose not obey such order requirement,
    therefore when "prate_section" is "HT", when comparing from tail to head,
    it will lead to access out of bounds in _rtl8812ae_eq_n_byte(). As
    mentioned above, the _rtl8812ae_eq_n_byte() has the same function as
    strcmp(), so just strcmp() is enough.
    
    Fix it by removing _rtl8812ae_eq_n_byte() and use strcmp() barely.
    Although it can be fixed by adjusting the comparison order of
    "prate_section", this may cause the value of "rate_section" to not be
    from 0 to 5. In addition, commit "21e4b072" not only moved driver
    from staging to regular tree, but also added setting txpower limit
    function during the driver config phase, so the problem was introduced
    by this commit.
    
    Fixes: 21e4b072 ("rtlwifi: rtl8821ae: Move driver from staging to regular tree")
    Signed-off-by: default avatarLi Zetao <lizetao1@huawei.com>
    Acked-by: default avatarPing-Ke Shih <pkshih@realtek.com>
    Signed-off-by: default avatarKalle Valo <kvalo@kernel.org>
    Link: https://lore.kernel.org/r/20221212025812.1541311-1-lizetao1@huawei.com
    117dbeda
phy.c 142 KB