Summary

psp_v10_0_compare_sram_data L435 while(!ucode_size) should be while(ucode_size). Normal case ucode_size>0: !ucode_size=false loop body NEVER executes function unconditionally returns true SRAM-vs-firmware integrity verification silently disabled on Raven/Raven2/Picasso. Sibling psp_v3_1.c:555 and psp_v11_0.c:500 both correctly use while(ucode_size). Degenerate ucode_size==0 case (craftable firmware ucode_size_bytes=0 passes validate): loop runs once derefs *ucode_mem uninitialized heap then ucode_size-=4 underflows UINT_MAX-3 !ucode_size false exits true. LATENT: amdgpu_psp_check_fw_loading_status amdgpu_psp.c:547 inside #if 0 so function never called today. Fix: while(ucode_size).

PoC verification

Evidence pack

findings/poc/DF-1956 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	404 B	view raw
VERDICT.md	verdict	source-confirmation analysis	1.0 KB	↓ raw
build.sh	build-script	N/A (source-only)	65 B	view raw
run.sh	run-script	N/A (source-only)	89 B	view raw

VERDICT.md verdict source-confirmation analysis

↓ download raw

DF-1956 VERDICT

Verdict: REPRODUCED (source-confirmed)

Impact: Low (driver-level NULL deref / OOB / leak / DoS — hardware-gated)

Mechanism: psp_v10_0_compare_sram_data L435 while(!ucode_size) should be while(ucode_size). Normal case ucode_size>0: !ucode_size=false loop body NEVER executes function unconditionally returns true SRAM-vs-firm

Citation: sys/dev/drm/amd/amdgpu/psp_v10_0.c:433-443

Fix: Applied fix.diff — compiles in batch kernel build (rc=0, -Werror).

Verification method: Source-only line-by-line trace of cited path:line. Low-severity driver bug; PoC trigger requires specific hardware or root context. Confirmed the cited vulnerable pattern exists in source.

Fix status (batch validation)

Applied with the 36 sibling fix.diffs of this batch in findings/poc/_batch41/all_fixes.patch; single in-guest make -j6 nativekernel KERNCONF=X86_64_GENERIC completed RC=0 with zero errors under -Werror (full log: findings/poc/_batch41/fix_build8.log). Behavior A/B intentionally skipped for this Info-tier item.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

fix.diff compiled in batch kernel build rc=0 -Werror

fix.diff compiled in batch kernel build rc=0 -Werror

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: while(!ucode_size) inverted — SRAM verification never runs (psp_v10_0.c:433-443)

Verified recommended fix

Source-confirmed: while(!ucode_size) inverted — SRAM verification never runs (psp_v10_0.c:433-443)

Verdict