RE: [PATCH v3] rtlwifi: rtl8821ae: Fix global-out-of-bounds bug in _rtl8812ae_phy_set_txpower_limit()

[Ping-Ke Shih <pkshih@realtek.com>]

> -----Original Message-----
> From: Ping-Ke Shih
> Sent: Monday, December 12, 2022 9:35 AM
> To: 'Li Zetao' <lizetao1@huawei.com>
> Cc: Larry.Finger@lwfinger.net; davem@davemloft.net; edumazet@google.com; kuba@kernel.org;
> kvalo@kernel.org; linux-kernel@vger.kernel.org; linux-wireless@vger.kernel.org; linville@tuxdriver.com;
> netdev@vger.kernel.org; pabeni@redhat.com
> Subject: RE: [PATCH v3] rtlwifi: rtl8821ae: Fix global-out-of-bounds bug in
> _rtl8812ae_phy_set_txpower_limit()
> 
> 
> 
> > -----Original Message-----
> > From: Li Zetao <lizetao1@huawei.com>
> > Sent: Monday, December 12, 2022 10:36 AM
> > To: Ping-Ke Shih <pkshih@realtek.com>
> > Cc: Larry.Finger@lwfinger.net; davem@davemloft.net; edumazet@google.com; kuba@kernel.org;
> > kvalo@kernel.org; linux-kernel@vger.kernel.org; linux-wireless@vger.kernel.org;
> linville@tuxdriver.com;
> > lizetao1@huawei.com; netdev@vger.kernel.org; pabeni@redhat.com
> > Subject: [PATCH v3] rtlwifi: rtl8821ae: Fix global-out-of-bounds bug in
> _rtl8812ae_phy_set_txpower_limit()

Oops. Subject prefix should be "wifi: rtlwifi: ...".

If it isn't hard to you, please fix it, and add my acked-by along with v4.

> >
> > 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 "21e4b0726dc6" 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: 21e4b0726dc6 ("rtlwifi: rtl8821ae: Move driver from staging to regular tree")
> > Signed-off-by: Li Zetao <lizetao1@huawei.com>
> 
> Thanks for your fix.
> 
> Acked-by: Ping-Ke Shih <pkshih@realtek.com>
> 
> > ---
> > v1 -> v2: delete the third parameter of _rtl8812ae_eq_n_byte() and use
> > strcmp to replace loop comparison.
> > v2 -> v3: remove _rtl8812ae_eq_n_byte() and use strcmp() barely.
> >
> >  .../wireless/realtek/rtlwifi/rtl8821ae/phy.c  | 52 +++++++------------
> >  1 file changed, 20 insertions(+), 32 deletions(-)
> >
> 
> [...]