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commitc033a38a81upstream. In commit8c89f7b3d3("mac80211: Use flex-array for radiotap header bitmap") we accidentally pointed the position to the wrong place, so we overwrite a present bitmap, and thus cause all kinds of trouble. To see the issue, note that the previous code read: pos = (void *)(it_present + 1); The requirement now is that we need to calculate pos via it_optional, to not trigger the compiler hardening checks, as: pos = (void *)&rthdr->it_optional[...]; Rewriting the original expression, we get (obviously, since that just adds "+ x - x" terms): pos = (void *)(it_present + 1 + rthdr->it_optional - rthdr->it_optional) and moving the "+ rthdr->it_optional" outside to be used as an array: pos = (void *)&rthdr->it_optional[it_present + 1 - rthdr->it_optional]; The original is off by one, fix it. Cc: stable@vger.kernel.org Fixes:8c89f7b3d3("mac80211: Use flex-array for radiotap header bitmap") Reported-by: Sid Hayn <sidhayn@gmail.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Tested-by: Sid Hayn <sidhayn@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20211109100203.c61007433ed6.I1dade57aba7de9c4f48d68249adbae62636fd98c@changeid Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.