Messages in this thread | | | Subject | Re: [PATCH] scsi: core: initialize cmd->cmnd before it is used | From | Douglas Gilbert <> | Date | Tue, 2 Nov 2021 17:33:51 -0400 |
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On 2021-11-01 11:06 p.m., Bart Van Assche wrote: > On 11/1/21 18:56, Douglas Gilbert wrote: >> On 2021-11-01 4:20 p.m., Bart Van Assche wrote: >>> One of the functions in the call stack in the first message of this email >>> thread is sg_io(). I am not aware of any documentation that specifies whether >>> it is valid to set cmd_len in the sg_io header to zero. My opinion is that >>> the SG_IO implementation should either reject cmd_len == 0 or set cmd_len >>> to a valid value if it is zero. >> >> For the sg driver in production, the v3 interface users (including >> ioctl(<sg_fd>, SG_IO,) ) have this check: >> >> if ((!hp->cmdp) || (hp->cmd_len < 6) || (hp->cmd_len > sizeof (cmnd))) { >> sg_remove_request(sfp, srp); >> return -EMSGSIZE; >> } > > Hi Doug, > > Thanks for having taken a look. I found the above check in sg_new_write(). To me > that function seems to come from a code path that is unrelated to sg_io(), the > function shown in the call stack in the email at the start of this thread. Maybe > I overlooked something but I haven't found a minimum size check for hdr->cmd_len > in sg_io() before the blk_execute_rq() call. Should such a check perhaps be added?
I guess it came from ioctl(<non_sg_fd>, SG_IO, ) and I found no lower bound check when I looked in lk 5.15.0 . No-one has complained to me about the hp->cmd_len < 6
check in the sg driver ***. So I think such a check may be useful in the scsi_fill_sghdr_rq() function in drivers/scsi/scsi_ioctl.c . And a return of -EMSGSIZE seems to be tailor made for this situation.
Doug Gilbert
*** It is possible a vendor specific command could be between 1 and 5 bytes long, but that would probably be an unwise choice.
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