As reported by Reobert O'Callahan, since Viro's commit to kill dev_ifsioc() we attempt to copy too much data in compat mode, which may lead to EFAULT when the 32-bit version of struct ifreq sits at/near the end of a page boundary, and the next page isn't mapped. Fix this by passing the approprate compat/non-compat size to copy and using that, as before the dev_ifsioc() removal. This works because only the embedded "struct ifmap" has different size, and this is only used in SIOCGIFMAP/SIOCSIFMAP which has a different handler. All other parts of the union are naturally compatible. This fixes https://bugzilla.kernel.org/show_bug.cgi?id=199469. Fixes: bf4405737f9f ("kill dev_ifsioc()") Reported-by: Robert O'Callahan <robert@ocallahan.org> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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.
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