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-rw-r--r--security/keys/keyring.c39
1 files changed, 19 insertions, 20 deletions
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index a7e51f793867..36f842ec87f0 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -459,34 +459,33 @@ static long keyring_read(const struct key *keyring,
char __user *buffer, size_t buflen)
{
struct keyring_read_iterator_context ctx;
- unsigned long nr_keys;
- int ret;
+ long ret;
kenter("{%d},,%zu", key_serial(keyring), buflen);
if (buflen & (sizeof(key_serial_t) - 1))
return -EINVAL;
- nr_keys = keyring->keys.nr_leaves_on_tree;
- if (nr_keys == 0)
- return 0;
-
- /* Calculate how much data we could return */
- if (!buffer || !buflen)
- return nr_keys * sizeof(key_serial_t);
-
- /* Copy the IDs of the subscribed keys into the buffer */
- ctx.buffer = (key_serial_t __user *)buffer;
- ctx.buflen = buflen;
- ctx.count = 0;
- ret = assoc_array_iterate(&keyring->keys, keyring_read_iterator, &ctx);
- if (ret < 0) {
- kleave(" = %d [iterate]", ret);
- return ret;
+ /* Copy as many key IDs as fit into the buffer */
+ if (buffer && buflen) {
+ ctx.buffer = (key_serial_t __user *)buffer;
+ ctx.buflen = buflen;
+ ctx.count = 0;
+ ret = assoc_array_iterate(&keyring->keys,
+ keyring_read_iterator, &ctx);
+ if (ret < 0) {
+ kleave(" = %ld [iterate]", ret);
+ return ret;
+ }
}
- kleave(" = %zu [ok]", ctx.count);
- return ctx.count;
+ /* Return the size of the buffer needed */
+ ret = keyring->keys.nr_leaves_on_tree * sizeof(key_serial_t);
+ if (ret <= buflen)
+ kleave("= %ld [ok]", ret);
+ else
+ kleave("= %ld [buffer too small]", ret);
+ return ret;
}
/*