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f075dce66c
The SCSI_IOCTL_SEND_COMMAND ioctl has interesting scsi command "security" checking. If the file was opened read-only (but only in that case), it will fetch the first byte of the command from user space, and do "sg_allow_access()" on it. That, in turn, will check that "blk_verify_command()" is ok with that command byte. If that passes, it will then do call "sg_scsi_ioctl()" to execute the command. This is entirely nonsensical for several reasons. It's nonsensical simply because it's racy: after it copies the command byte from user mode to check it, user mode could just change the byte before it is actually submitted later by "sg_scsi_ioctl()". But it is nonsensical also because "sg_scsi_ioctl()" itself already does blk_verify_command() on the command properly after it has been copied from user space. So it is an incorrect implementation of a pointless check. Remove it. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.