Re: [PATCH v1] scsi: ufs: scsi_get_lba error fix by check cmd opcode

[Bart Van Assche <bvanassche@acm.org>]

On 3/7/22 03:17, peter.wang@mediatek.com wrote:
> When ufs init without scmd->device->sector_size set,
> scsi_get_lba will get a wrong shift number and ubsan error.
> shift exponent 4294967286 is too large for 64-bit type
> 'sector_t' (aka 'unsigned long long')
> Call scsi_get_lba only when opcode is READ_10/WRITE_10/UNMAP.

Hmm ... how can it happen that sector_size has not been set? I think 
that can only happen for LUNs of type SCSI DISK if sd_read_capacity() 
fails? If sd_read_capacity() fails I think the sd driver is expected to 
set the capacity to zero?

rq->__sector == -1 for flush requests and the type of that member 
(sector_t) is unsigned. I think that it is allowed for a shift left of 
an unsigned type to overflow. From the C standard: "The result of E1 << 
E2 is E1 left-shifted E2 bit positions; vacated bits are filled with
zeros. If E1 has an unsigned type, the value of the result is E1 × 2E2 , 
reduced modulo one more than the maximum value representable in the 
result type."

Thanks,

Bart.