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author | David Howells <dhowells@redhat.com> | 2019-08-19 18:02:01 +0300 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-08-19 19:43:57 +0300 |
commit | 555df336c754ac9de1af9a5c72508918b3796b18 (patch) | |
tree | 74c2cd33ccf1b26ab9720d563d8057ca68c6c6fd /include | |
parent | d1abaeb3be7b5fa6d7a1fbbd2e14e3310005c4c1 (diff) | |
download | linux-555df336c754ac9de1af9a5c72508918b3796b18.tar.xz |
keys: Fix description size
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>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/key.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/include/linux/key.h b/include/linux/key.h index 91f391cd272e..50028338a4cc 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -94,11 +94,11 @@ struct keyring_index_key { union { struct { #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */ - u8 desc_len; - char desc[sizeof(long) - 1]; /* First few chars of description */ + u16 desc_len; + char desc[sizeof(long) - 2]; /* First few chars of description */ #else - char desc[sizeof(long) - 1]; /* First few chars of description */ - u8 desc_len; + char desc[sizeof(long) - 2]; /* First few chars of description */ + u16 desc_len; #endif }; unsigned long x; |