d366f51305
[ Upstream commit bb2ba2d75a2d673e76ddaf13a9bd30d6a8b1bb08 ]
Fix the creation of shortcuts for which the length of the index key value
is an exact multiple of the machine word size. The problem is that the
code that blanks off the unused bits of the shortcut value malfunctions if
the number of bits in the last word equals machine word size. This is due
to the "<<" operator being given a shift of zero in this case, and so the
mask that should be all zeros is all ones instead. This causes the
subsequent masking operation to clear everything rather than clearing
nothing.
Ordinarily, the presence of the hash at the beginning of the tree index key
makes the issue very hard to test for, but in this case, it was encountered
due to a development mistake that caused the hash output to be either 0
(keyring) or 1 (non-keyring) only. This made it susceptible to the
keyctl/unlink/valid test in the keyutils package.
The fix is simply to skip the blanking if the shift would be 0. For
example, an index key that is 64 bits long would produce a 0 shift and thus
a 'blank' of all 1s. This would then be inverted and AND'd onto the
index_key, incorrectly clearing the entire last word.
Fixes: 3cb989501c26 ("Add a generic associative array implementation.")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.