4280a0a701
strncpy() is deprecated for use on NUL-terminated destination strings [1]
and as such we should prefer more robust and less ambiguous string
interfaces.
Since all these structs are copied out to userspace let's keep them
NUL-padded by using strscpy_pad() which guarantees NUL-termination of the
destination buffer while also providing the NUL-padding behavior that
strncpy() has.
Let's also opt to use the more idiomatic strscpy() usage of: 'dest, src,
sizeof(dest)' in cases where the compiler can determine the size of the
destination buffer. Do this for all cases of strscpy...() in this file.
To be abundantly sure we don't leak stack data out to user space let's also
change a strscpy() to strscpy_pad(). This strscpy() was introduced in
commit dbe37c71d124 ("scsi: message: fusion: Replace all non-returning
strlcpy() with strscpy()")
Note that since we are creating these structs with a copy_from_user() and
modifying fields and then copying back out to the user it is probably OK
not to explicitly NUL-pad everything as any data leak is probably just data
from the user themselves. If this is too eager, let's opt for strscpy()
which is still in the spirit of removing deprecated strncpy() usage
treewide.
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20230927-strncpy-drivers-message-fusion-mptctl-c-v1-1-bb2eddc1743c@google.com
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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.
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.