[UPDATE 3] SM-F956B — The anti-rollback system is cracked open, and Samsung's "Safeplace" is beaten

Short version: the security coprocessor that enforces Samsung's anti-rollback fuses is sitting in the bootloader tar as PLAINTEXT RISC-V firmware, and we've mapped the entire enforcement chain. Plus a working DEFEX bypass. Details below.

============== 1. THE ANTI-ROLLBACK MANAGER IS A TME — AND IT'S RISC-V ============== The xbl_s.melf in Samsung's BL tar isn't AArch64. Its ELF header says e_machine = 0xF3 = EM_RISCV. It's the TME (Trusted Management Engine) — Qualcomm's "Aurora" security coprocessor running FreeRTOS — and it contains services/antirollback/src/AntiRollbackMgr.cpp with the config surface:

ARBConfig:MAX_NUM_ARB_ADDRESS
ARBConfig:arbFuseMapQti
ARBConfig:arbFuseMapOem
"Static Fuse Overwrite"
"This device is using RT Fuse Val" / "HT Fuse Val"

The fuse maps are CONFIG-DRIVEN and there's a static-override string in the binary. The ARB decision isn't pure hardware — there's a software path to audit. The TME code is in the file you can download from FUS right now. (Credit to gdrci/Research for independently mapping the TME blob locations — we're building on their map.)

The TZ side is mapped too: qsee_sfs_is_anti_rollback_enabled (object 0x91, cached flag at tpidrro+0x18ac) and an OEM spare-fuse WRITER (gated by permissions 0x12 + /ac/oem_regions_config). The writer exists in shipped firmware.

============== 2. SAMSUNG'S "SAFEPLACE" EXEC KILL — BYPASSED, VERIFIED ON DEVICE ============== Samsung's DEFEX Safeplace SIGKILLs any /data binary exec'd from a root sh. The bypass we verified live: bind-mount the binary over a /system/bin path and exec that path.

mount --bind /data/local/tmp/mybin /system/bin/logcat
/system/bin/logcat    # runs as uid 0, no kill
umount /system/bin/logcat

General-purpose: any binary you build now runs as root. (The S918U GhostLock port uses the same trick in a private mount ns for its KernelSU late-load — now confirmed on the F956B.)

============== 3. THE REST OF THE BOARD (quick) ============== - CVE-2026-24090 unlock path: the avb poc (Keymaster READ/WRITE_KM_DEVICE_STATE via qseecom) now RUNS on-device through the Safeplace bypass. One piece left: the boot-loaded keymaster TA's registry name (its partition label GUID is {a11d2a7c-d82a-4c2f-8a01-1805240e6626}). - QCOM VerifiedBoot protocol on Samsung DZI1 = GUID {8e5eff91-21b6-47d3-af2b-c15a-01e0-20ec} (the public PoC's variant — not the SM8850 one). - Temp root per boot (CVE-2026-43499): the payload rotates its own delay windows (40-90ms) with a persistent index — don't pin FOPS_DELAY_USEC, it disables the search. - Never take the October 2026 SMR.

Repos: github.com/plomens/f956b-bootchain-research · /android-rooting-field-guide · /rooting-breakthroughs (all public, all updated).