555df336c7
The maximum key description size is 4095. Commit f771fde82051 ("keys:
Simplify key description management") inadvertantly reduced that to 255
and made sizes between 256 and 4095 work weirdly, and any size whereby
size & 255 == 0 would cause an assertion in __key_link_begin() at the
following line:
BUG_ON(index_key->desc_len == 0);
This can be fixed by simply increasing the size of desc_len in struct
keyring_index_key to a u16.
Note the argument length test in keyutils only checked empty
descriptions and descriptions with a size around the limit (ie. 4095)
and not for all the values in between, so it missed this. This has been
addressed and
https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/keyutils.git/commit/?id=066bf56807c26cd3045a25f355b34c1d8a20a5aa
now exhaustively tests all possible lengths of type, description and
payload and then some.
The assertion failure looks something like:
kernel BUG at security/keys/keyring.c:1245!
...
RIP: 0010:__key_link_begin+0x88/0xa0
...
Call Trace:
key_create_or_update+0x211/0x4b0
__x64_sys_add_key+0x101/0x200
do_syscall_64+0x5b/0x1e0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
It can be triggered by:
keyctl add user "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" a @s
Fixes: f771fde82051 ("keys: Simplify key description management")
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: David Howells <dhowells@redhat.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.