tpm: Initialize name_size_alg for non-NULL name in tpm_buf_append_name()

tpm_buf_append_name() supports callers passing a pre-computed name
for handles. When name is non-NULL, the code skips the
tpm2_read_public() path but leaves name_size_alg uninitialized
before it is used as the memcpy size argument.

No current in-tree caller passes a non-NULL name, but future use
cases such as name caching would exercise this path. Initialize
name_size_alg by calling name_size() on the caller-provided name,
sharing the error check and assignment with the existing
tpm2_read_public() path. This prevents unmasking a latent bug when
the non-NULL name path is eventually used.

Assisted-by: Kiro:claude-opus-4.6
Reviewed-by: Justinien Bouron <jbouron@amazon.com>
Reviewed-by: Muhammad Hammad Ijaz <mhijaz@amazon.com>
Signed-off-by: Gunnar Kudrjavets <gunnarku@amazon.com>
Link: https://lore.kernel.org/r/20260510171152.4607-1-gunnarku@amazon.com
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index c4da6fde748f41adc8209800d2239a934c7efbb1..795cd99dc6fed6449adca059bf6eede8b1e046b7 100644 (file)
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -285,11 +285,14 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
            mso == TPM2_MSO_NVRAM) {
                if (!name) {
                        ret = tpm2_read_public(chip, handle, auth->name[slot]);
-                       if (ret < 0)
-                               goto err;
-
-                       name_size_alg = ret;
+               } else {
+                       ret = name_size(name);
                }
+
+               if (ret < 0)
+                       goto err;
+
+               name_size_alg = ret;
        } else {
                if (name) {
                        dev_err(&chip->dev, "handle 0x%08x does not use a name\n",