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strcpy() performs no bounds checking on the destination buffer. This could result in linear overflows beyond the end of the buffer, leading to all kinds of misbehavior. The safe replacement is strscpy(). [1][2] However, to simplify and clarify the code, to concatenate labels use the scnprintf() function. This way it is not necessary to check the return value of strscpy() (-E2BIG if the parameter count is 0 or the src was truncated) since scnprintf() always returns the number of chars written into the buffer. This function always returns a nul-terminated string even if it needs to be truncated. While at it, fix all other broken string generation code that wrongly interprets snprintf()'s return code or just uses sprintf(), implement that using scnprintf() here too. Drop breaks in loops around scnprintf() as it is safe now to loop. Moreover, the check is not needed: for the case when the buffer is exhausted, len never gets zero because scnprintf() takes the full buffer length as input parameter, but excludes the trailing '\0' in its return code and thus, 1 is the minimum len. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [2] https://github.com/KSPP/linux/issues/88 [ rric: Replace snprintf() with scnprintf(), rework sprintf() user, drop breaks in loops around scnprintf(), introduce 'end' pointer to reduce pointer arithmetic, use prefix pattern for e->location, adjust subject and description ] Co-developed-by: Joe Perches <joe@perches.com> Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Len Baker <len.baker@gmx.com> Signed-off-by: Robert Richter <rrichter@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210903150539.7282-1-len.baker@gmx.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.