Thread (3 messages) 3 messages, 3 authors, 2022-11-03

Re: [PATCH v2] net: mdio: fix undefined behavior in bit shift for __mdiobus_register

From: Andrew Lunn <andrew@lunn.ch>
Date: 2022-10-31 13:31:13

On Mon, Oct 31, 2022 at 09:26:45PM +0800, Gaosheng Cui wrote:
Shifting signed 32-bit value by 31 bits is undefined, so changing
significant bit to unsigned. The UBSAN warning calltrace like below:

UBSAN: shift-out-of-bounds in drivers/net/phy/mdio_bus.c:586:27
left shift of 1 by 31 places cannot be represented in type 'int'
Call Trace:
 <TASK>
 dump_stack_lvl+0x7d/0xa5
 dump_stack+0x15/0x1b
 ubsan_epilogue+0xe/0x4e
 __ubsan_handle_shift_out_of_bounds+0x1e7/0x20c
 __mdiobus_register+0x49d/0x4e0
 fixed_mdio_bus_init+0xd8/0x12d
 do_one_initcall+0x76/0x430
 kernel_init_freeable+0x3b3/0x422
 kernel_init+0x24/0x1e0
 ret_from_fork+0x1f/0x30
 </TASK>

Fixes: 4fd5f812c23c ("phylib: allow incremental scanning of an mii bus")
Signed-off-by: Gaosheng Cui <redacted>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew
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