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Commit 07b133e6060ba9de6cf6265fb23f0de8ec78e51c

Authored by Peter Huewe
Committed by Kent Yoder
1 parent 720ca4a9af
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

char/tpm: simplify duration calculation and eliminate smatch warning. 

This patch changes the semantics of the duration calculation for an
ordinal, by masking out the higher bits of a tpm command, which specify
whether it's an TPM_PROTECTED_COMMAND, TPM_UNPROTECTED_COMMAND,
TPM_CONNECTION_COMMAND, TPM_CONNECTION_COMMAND, TPM_VENDOR_COMMAND.
(See TPM Main Spec Part 2 Section 17 for details).

For all TPM_PROTECTED and TPM_CONNECTION commands the results are
unchanged.
The TPM_UNPROTECTED commands are TSS commands and thus irrelevant as
they are not sent to the tpm.
For vendor commands the semantics change for ordinals 10 and 11 but
they were probably wrong anyway.

For everything else which has the ordinal set to 10 or 11 the semantics
change as it now uses TPM_UNDEFINED instead of TPM_SHORT which was
probably wrong anyway (but irrelevant as not defined by the standard).

This patch also gets rid of the (false positive) smatch warning:
 drivers/char/tpm/tpm.c:360 tpm_calc_ordinal_duration() error: buffer
 overflow 'tpm_protected_ordinal_duration' 12 <= 243

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>

Showing 1 changed file with 6 additions and 7 deletions Side-by-side Diff

drivers/char/tpm/tpm.c
Diff comments   View file @ 07b133e
... ... @@ -40,8 +40,9 @@
40 40 };
41 41  
42 42 #define TPM_MAX_ORDINAL 243
43   -#define TPM_MAX_PROTECTED_ORDINAL 12
44   -#define TPM_PROTECTED_ORDINAL_MASK 0xFF
  43 +#define TSC_MAX_ORDINAL 12
  44 +#define TPM_PROTECTED_COMMAND 0x00
  45 +#define TPM_CONNECTION_COMMAND 0x40
45 46  
46 47 /*
47 48 * Bug workaround - some TPM's don't flush the most
48 49  
49 50  
... ... @@ -336,13 +337,11 @@
336 337 {
337 338 int duration_idx = TPM_UNDEFINED;
338 339 int duration = 0;
  340 + u8 category = (ordinal >> 24) & 0xFF;
339 341  
340   - if (ordinal < TPM_MAX_ORDINAL)
  342 + if ((category == TPM_PROTECTED_COMMAND && ordinal < TPM_MAX_ORDINAL) ||
  343 + (category == TPM_CONNECTION_COMMAND && ordinal < TSC_MAX_ORDINAL))
341 344 duration_idx = tpm_ordinal_duration[ordinal];
342   - else if ((ordinal & TPM_PROTECTED_ORDINAL_MASK) <
343   - TPM_MAX_PROTECTED_ORDINAL)
344   - duration_idx =
345   - tpm_ordinal_duration[ordinal & TPM_PROTECTED_ORDINAL_MASK];
346 345  
347 346 if (duration_idx != TPM_UNDEFINED)
348 347 duration = chip->vendor.duration[duration_idx];