Draft: [UPSTREAM] libutils: fault_mitigation: fix panic on hash mismatch
When running a test with CFG_FAULT_MITIGATION=y and with a corrupted message, hash verification fails and panic TEE core:
F/TC:? 0 trace_syscall:149 syscall #40 (syscall_asymm_verify) E/TC:2 0 Panic at lib/libutils/ext/fault_mitigation.c:87 <___ftmn_callee_done_check> E/TC:2 0 TEE load address @ 0x43200000 E/TC:2 0 Call stack: E/TC:2 0 0x4320a9f0 print_kernel_stack at optee-os/core/arch/arm/kernel/unwind_arm64.c:91 E/TC:2 0 0x432203fc __do_panic at optee-os/core/kernel/panic.c:26 (discriminator 32) E/TC:2 0 0x4327d324 ___ftmn_callee_done_check at optee-os/lib/libutils/ext/fault_mitigation.c:87 E/TC:2 0 0x43263aac __ftmn_callee_done_check at optee-os/lib/libutils/ext/include/fault_mitigation.h:349 E/TC:2 0 0x43258408 sw_crypto_acipher_rsassa_verify at optee-os/core/lib/libtomcrypt/rsa.c:669 E/TC:2 0 0x43247ecc syscall_asymm_verify at optee-os/core/tee/tee_svc_cryp.c:4420 E/TC:2 0 0x43206d18 scall_do_call at optee-os/core/arch/arm/kernel/arch_scall_a64.S:140 E/TC:2 0 0x43206798 thread_scall_handler at optee-os/core/arch/arm/kernel/thread.c:1115 E/TC:2 0 0x432043e8 el0_svc at optee-os/core/arch/arm/kernel/thread_a64.S:850
Function ftmn_set_check_res_memcmp() is currently used on the verification of RSA hash. When CFG_FAULT_MITIGATION flag is enabled, ftmn.check.res is set with the return value of the hash comparison. This can be 0, when hash matches, or another number, positive or negativen, when hash does not match.
For fault mitigation purposes, the value stored on ftmn.check.res is later compared with the result of the signature comparison, which can assume only two values : 1==valid or 0==invalid.
With that, ftmn_set_check_res_memcmp() should set ftmn.check.res either with 0, when hash matches, or with 1, when hash does not match. Fix ___ftmn_set_check_res_memcmp() to have this behavior. Note that, the fault mitigation check is done bewteen ftmn.check.res and !*stat.
Signed-off-by: Felix Freimann felix.freimann@mediatek.com Signed-off-by: Vitor Sato Eschholz vsatoes@baylibre.com
Closes RITA-1237