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authorEric Biggers <ebiggers@google.com>2019-02-22 15:36:18 +0000
committerJames Morris <james.morris@microsoft.com>2019-02-22 10:11:34 -0800
commitede0fa98a900e657d1fcd80b50920efc896c1a4c (patch)
tree6bb852b833c21e0e57fb4de6c67d0755fde4d53d /security
parentKEYS: user: Align the payload buffer (diff)
downloadlinux-dev-ede0fa98a900e657d1fcd80b50920efc896c1a4c.tar.xz
linux-dev-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')
-rw-r--r--security/keys/keyring.c4
-rw-r--r--security/keys/proc.c3
-rw-r--r--security/keys/request_key.c1
-rw-r--r--security/keys/request_key_auth.c2
4 files changed, 4 insertions, 6 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,
diff --git a/security/keys/proc.c b/security/keys/proc.c
index d2b802072693..78ac305d715e 100644
--- a/security/keys/proc.c
+++ b/security/keys/proc.c
@@ -165,8 +165,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
int rc;
struct keyring_search_context ctx = {
- .index_key.type = key->type,
- .index_key.description = key->description,
+ .index_key = key->index_key,
.cred = m->file->f_cred,
.match_data.cmp = lookup_user_key_possessed,
.match_data.raw_data = key,
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 3f56a312dd35..7a0c6b666ff0 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -531,6 +531,7 @@ struct key *request_key_and_link(struct key_type *type,
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,
diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
index afc304e8b61e..bda6201c6c45 100644
--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -247,7 +247,7 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id)
struct key *authkey;
key_ref_t authkey_ref;
- sprintf(description, "%x", target_id);
+ ctx.index_key.desc_len = sprintf(description, "%x", target_id);
authkey_ref = search_process_keyrings(&ctx);