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978ffcbf00
No point in allocating a new mm, counting arguments and environment variables etc if we're just going to return ENOENT. This patch does expose the fact that 'do_filp_open()' that execve() uses is still unnecessarily expensive in the failure case, because it allocates the 'struct file *' early, even if the path lookup (which is heavily optimized) fails. So that remains an unnecessary cost in the "no such executable" case, but it's a separate issue. Regardless, I do not want to do _both_ a filename_lookup() and a later do_filp_open() like the origin patch by Josh Triplett did in [1]. Reported-by: Josh Triplett <josh@joshtriplett.org> Cc: Kees Cook <keescook@chromium.org> Cc: Mateusz Guzik <mjguzik@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Link: https://lore.kernel.org/lkml/5c7333ea4bec2fad1b47a8fa2db7c31e4ffc4f14.1663334978.git.josh@joshtriplett.org/ [1] Link: https://lore.kernel.org/lkml/202209161637.9EDAF6B18@keescook/ Link: https://lore.kernel.org/lkml/CAHk-=wgznerM-xs+x+krDfE7eVBiy_HOam35rbsFMMOwvYuEKQ@mail.gmail.com/ Link: https://lore.kernel.org/lkml/CAHk-=whf9qLO8ipps4QhmS0BkM8mtWJhvnuDSdtw5gFjhzvKNA@mail.gmail.com/ 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.
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.