[PATCH v3 5/7] KEYS: load key flags and expiry time atomically in keyring_search_iterator()

[Eric Biggers]

From: Eric Biggers <ebigg...@google.com>

Similar to the case for key_validate(), we should load the key ->flags
and ->expiry once atomically in keyring_search_iterator(), since they
can be changed concurrently whenever the key semaphore isn't held.

Signed-off-by: Eric Biggers <ebigg...@google.com>
---
 security/keys/keyring.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index e54ad0ed7aa4..cb39b517f69c 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -553,7 +553,7 @@ static int keyring_search_iterator(const void *object, void 
*iterator_data)
 {
        struct keyring_search_context *ctx = iterator_data;
        const struct key *key = keyring_ptr_to_key(object);
-       unsigned long kflags = key->flags;
+       unsigned long kflags = READ_ONCE(key->flags);
 
        kenter("{%d}", key->serial);
 
@@ -565,6 +565,8 @@ static int keyring_search_iterator(const void *object, void 
*iterator_data)
 
        /* skip invalidated, revoked and expired keys */
        if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
+               time_t expiry = READ_ONCE(key->expiry);
+
                if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
                              (1 << KEY_FLAG_REVOKED))) {
                        ctx->result = ERR_PTR(-EKEYREVOKED);
@@ -572,7 +574,7 @@ static int keyring_search_iterator(const void *object, void 
*iterator_data)
                        goto skipped;
                }
 
-               if (key->expiry && ctx->now.tv_sec >= key->expiry) {
+               if (expiry && ctx->now.tv_sec >= expiry) {
                        if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
                                ctx->result = ERR_PTR(-EKEYEXPIRED);
                        kleave(" = %d [expire]", ctx->skipped_ret);
-- 
2.14.2.822.g60be5d43e6-goog