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| author |   Eric Biggers <ebiggers@google.com> | 2019-02-22 15:36:18 +0000 |
|---|---|---|
| committer |   James Morris <james.morris@microsoft.com> | 2019-02-22 10:11:34 -0800 |
| commit | ede0fa98a900e657d1fcd80b50920efc896c1a4c (patch) | |
| tree | 6bb852b833c21e0e57fb4de6c67d0755fde4d53d /security/keys/keyring.c | |
| parent | KEYS: user: Align the payload buffer (diff) | |
| download | wireguard-linux-ede0fa98a900e657d1fcd80b50920efc896c1a4c.tar.xz wireguard-linux-ede0fa98a900e657d1fcd80b50920efc896c1a4c.zip | |
KEYS: always initialize keyring_index_key::desc_len
syzbot hit the 'BUG_ON(index_key->desc_len == 0);' in __key_link_begin()
called from construct_alloc_key() during sys_request_key(), because the
length of the key description was never calculated.
The problem is that we rely on ->desc_len being initialized by
search_process_keyrings(), specifically by search_nested_keyrings().
But, if the process isn't subscribed to any keyrings that never happens.
Fix it by always initializing keyring_index_key::desc_len as soon as the
description is set, like we already do in some places.
The following program reproduces the BUG_ON() when it's run as root and
no session keyring has been installed. If it doesn't work, try removing
pam_keyinit.so from /etc/pam.d/login and rebooting.
#include <stdlib.h>
#include <unistd.h>
#include <keyutils.h>
int main(void)
{
int id = add_key("keyring", "syz", NULL, 0, KEY_SPEC_USER_KEYRING);
keyctl_setperm(id, KEY_OTH_WRITE);
setreuid(5000, 5000);
request_key("user", "desc", "", id);
}
Reported-by: syzbot+ec24e95ea483de0a24da@syzkaller.appspotmail.com
Fixes: b2a4df200d57 ("KEYS: Expand the capacity of a keyring")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: James Morris <james.morris@microsoft.com>
Diffstat (limited to 'security/keys/keyring.c')
| -rw-r--r-- | security/keys/keyring.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/security/keys/keyring.c b/security/keys/keyring.c index eadebb92986a..f81372f53dd7 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -661,9 +661,6 @@ static bool search_nested_keyrings(struct key *keyring, BUG_ON((ctx->flags & STATE_CHECKS) == 0 || (ctx->flags & STATE_CHECKS) == STATE_CHECKS); - if (ctx->index_key.description) - ctx->index_key.desc_len = strlen(ctx->index_key.description); - /* Check to see if this top-level keyring is what we are looking for * and whether it is valid or not. */ @@ -914,6 +911,7 @@ key_ref_t keyring_search(key_ref_t keyring, struct keyring_search_context ctx = { .index_key.type = type, .index_key.description = description, + .index_key.desc_len = strlen(description), .cred = current_cred(), .match_data.cmp = key_default_cmp, .match_data.raw_data = description, |