linux_dsm_epyc7002/drivers/char/tpm
Gustavo A. R. Silva ab91c2a89f tpm: eventlog: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.

Also, the following issue shows up due to the flexible-array member
having incomplete type[4]:

drivers/char/tpm/eventlog/tpm2.c: In function ‘tpm2_bios_measurements_start’:
drivers/char/tpm/eventlog/tpm2.c:54:46: error: invalid application of ‘sizeof’ to incomplete type ‘u8[]’ {aka ‘unsigned char[]’}
   54 |  size = sizeof(struct tcg_pcr_event) - sizeof(event_header->event)
      |                                              ^
drivers/char/tpm/eventlog/tpm2.c: In function ‘tpm2_bios_measurements_next’:
drivers/char/tpm/eventlog/tpm2.c:102:10: error: invalid application of ‘sizeof’ to incomplete type ‘u8[]’ {aka ‘unsigned char[]’}
  102 |    sizeof(event_header->event) + event_header->event_size;
      |          ^
drivers/char/tpm/eventlog/tpm2.c: In function ‘tpm2_binary_bios_measurements_show’:
drivers/char/tpm/eventlog/tpm2.c:140:10: error: invalid application of ‘sizeof’ to incomplete type ‘u8[]’ {aka ‘unsigned char[]’}
  140 |    sizeof(event_header->event) + event_header->event_size;
      |          ^
scripts/Makefile.build:266: recipe for target 'drivers/char/tpm/eventlog/tpm2.o' failed
make[3]: *** [drivers/char/tpm/eventlog/tpm2.o] Error 1

As mentioned above: "Flexible array members have incomplete type, and
so the sizeof operator may not be applied. As a quirk of the original
implementation of zero-length arrays, sizeof evaluates to zero."[1] As
in "sizeof(event_header->event) always evaluated to 0, so removing it
has no effect".

Lastly, make use of the struct_size() helper to deal with the
flexible array member and its host structure.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
[4] https://github.com/KSPP/linux/issues/43

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2020-05-22 18:50:12 +03:00
..
eventlog tpm: eventlog: Replace zero-length array with flexible-array member 2020-05-22 18:50:12 +03:00
st33zp24
Kconfig tpm: tpm_tis_spi: Support cr50 devices 2019-11-12 21:45:37 +02:00
Makefile tpm: Revert tpm_tis_spi_mod.ko to tpm_tis_spi.ko. 2020-02-17 20:46:34 +02:00
tpm1-cmd.c tpm: provide a way to override the chip returned durations 2019-11-12 21:45:36 +02:00
tpm2-cmd.c tpm: Export tpm2_get_cc_attrs_tbl for ibmvtpm driver as module 2020-04-21 00:06:13 +03:00
tpm2-space.c
tpm_atmel.c
tpm_atmel.h
tpm_crb.c tpm_crb: fix fTPM on AMD Zen+ CPUs 2019-11-12 21:45:37 +02:00
tpm_ftpm_tee.c tpm/tpm_ftpm_tee: Use UUID API for exporting the UUID 2020-05-22 18:50:12 +03:00
tpm_ftpm_tee.h tpm/tpm_ftpm_tee: A driver for firmware TPM running inside TEE 2019-09-02 17:08:35 +03:00
tpm_i2c_atmel.c
tpm_i2c_infineon.c
tpm_i2c_nuvoton.c
tpm_ibmvtpm.c tpm: ibmvtpm: retry on H_CLOSED in tpm_ibmvtpm_send() 2020-04-21 00:06:13 +03:00
tpm_ibmvtpm.h tpm: ibmvtpm: Wait for buffer to be set before proceeding 2020-03-15 20:12:52 +02:00
tpm_infineon.c
tpm_nsc.c
tpm_ppi.c
tpm_tis_core.c tpm/tpm_tis: Free IRQ if probing fails 2020-04-21 00:06:13 +03:00
tpm_tis_core.h
tpm_tis_spi_cr50.c tpm: tpm_tis_spi_cr50: use new structure for SPI transfer delays 2020-03-13 03:53:16 +02:00
tpm_tis_spi_main.c tpm_tis_spi: use new 'delay' structure for SPI transfer delays 2020-03-13 03:53:16 +02:00
tpm_tis_spi.h tpm: tpm_tis_spi: Support cr50 devices 2019-11-12 21:45:37 +02:00
tpm_tis.c tpm: Switch to platform_get_irq_optional() 2019-11-12 21:45:37 +02:00
tpm_vtpm_proxy.c compat_ioctl: move drivers to compat_ptr_ioctl 2019-10-23 17:23:43 +02:00
tpm-chip.c sysfs: remove redundant __compat_only_sysfs_link_entry_to_kobj fn 2020-04-05 11:34:35 -07:00
tpm-dev-common.c tpm: Handle negative priv->response_len in tpm_common_read() 2020-01-08 18:11:09 +02:00
tpm-dev.c
tpm-dev.h tpm: Handle negative priv->response_len in tpm_common_read() 2020-01-08 18:11:09 +02:00
tpm-interface.c tpm: fix wrong return value in tpm_pcr_extend 2020-04-21 00:06:13 +03:00
tpm-sysfs.c tpm: Add tpm_version_major sysfs file 2020-01-22 10:46:51 +02:00
tpm.h tpm: ibmvtpm: Add support for TPM2 2020-03-15 20:13:33 +02:00
tpmrm-dev.c
xen-tpmfront.c