Re:Re: [PATCH] net: phy: microchip_t1: fix NULL pointer dereference in lan887x_phy_init()

[huhai <15815827059@163.com>]

At 2026-09-03 06:58:25, "Jakub Kicinski" <kuba@kernel.org> wrote:
>On Wed, 2 Sep 2026 17:16:48 +0800 Xuanqiang Luo wrote:
>> > mchp_rds_ptp_probe() may return NULL when CONFIG_PTP_1588_CLOCK is disabled.  
>> 
>> When CONFIG_MICROCHIP_PHY_RDS_PTP=n, the stub for
>> mchp_rds_ptp_probe() also returns NULL, even if
>> CONFIG_PTP_1588_CLOCK=y. Please mention this case in the commit message.
>
>Speaking of improvements to the commits message - please also explain
>how the issue was found, reproduced, and fix validated.
>

The issue was discovered via smatch:

make CHECK="smatch -p=kernel"  C=2  drivers/net/phy/microchip_t1.o
  CHECK   scripts/mod/empty.c
  DESCEND objtool
  CHECK   drivers/net/phy/microchip_t1.c
drivers/net/phy/microchip_t1.c:1295 lan887x_phy_init() warn: 'priv->clock' can also be NULL

I will add the above information to the commit message in the next version of the patch.

Then, disassembly confirmed that a null pointer dereference does indeed exist:

objdump -drSwC --no-show-raw-insn --disassemble=lan887x_phy_init drivers/net/phy/microchip_t1.o
             	priv->clock = mchp_rds_ptp_probe(phydev, MDIO_MMD_VEND1,
    10c2:       movq   $0x0,0x30(%r13)   # priv->clock = NULL
                ... ...
                priv->clock->event_pin = 3;
    10e7:       mov    0x30(%r13),%rax   # rax = priv->clock = NULL
    10eb:       movl   $0x3,0x190(%rax)  # *(u32 *)(NULL + 0x190) = 3

Additionally, I do not have hardware available to verify and reproduce the issue,
it was identified purely through analysis. After applying a patch, smatch no longer 
produces the warning.

>It'd be good to improve the spalling of your name (rather just
>repeating your email login) a little; or just add your real name in
>unicode characters in () brackets, like huhai ($unicode chars) <email>.

Regarding the name spelling suggestion, I will update my signed-off-by
line to use my full English name in the next version of the patch.

Thanks.