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    Subject[PATCH v3 5/7] KEYS: load key flags and expiry time atomically in keyring_search_iterator()
    Date
    From: Eric Biggers <ebiggers@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 <ebiggers@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
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