[PATCH 0/5] tpm: assorted fixes and cleanups

[Pei Xiao <xiaopei01@kylinos.cn>]

This series fixes several issues found during a code review of
drivers/char/tpm:

  1. tpm_ppi: tpm_show_ppi_response() stores its return value in an
     acpi_status (a u32 typedef), so error codes such as -EINVAL reach
     user space as huge positive values.  Declare the variable as
     ssize_t to match the show callback's return type.

  2. tpm_nsc: tpm_nsc_remove() doubles as the release callback of the
     hand-created platform device and dereferences the chip drvdata
     unconditionally; init failures before tpmm_chip_alloc() crash
     module load.  Return early when the chip has not been created.

  3. tpm_nsc: the cleanup runs twice on module exit because
     tpm_nsc_remove() is both the explicit cleanup and the device
     release callback; the second run operates on an already freed
     chip.  Stop overriding the release callback, which also stops the
     platform object allocation from leaking.

  4. tpm_dev: a zero-length read() discards a pending response,
     breaking the command/response pairing of the TPM character
     devices, although POSIX requires zero-count reads to have no side
     effects.  Return early on a zero count.

  5. tpm-interface: make the tpm_init() error messages consistently
     prefixed with "tpm: " and report the actual failure of
     tpm_dev_common_init().

The series was prepared with AI assistance (GLM-5.3); every change was
reviewed against the code by hand.

Pei Xiao (5):
  tpm: tpm_ppi: fix wrong error code returned to user space
  tpm: tpm_nsc: fix NULL pointer dereference on init failure
  tpm: tpm_nsc: stop using the cleanup callback as dev.release
  tpm: fix zero-length read discarding the pending response
  tpm: fix log messages in tpm_init()

 drivers/char/tpm/tpm-dev-common.c | 3 +++
 drivers/char/tpm/tpm-interface.c  | 6 +++---
 drivers/char/tpm/tpm_nsc.c        | 8 ++++++--
 drivers/char/tpm/tpm_ppi.c        | 2 +-
 4 files changed, 13 insertions(+), 6 deletions(-)

-- 
2.25.1