Summary

powernow.c L343 static char freqs_available[80]. L380 freq_len=n_states*(sizeof(9999 )-1)+1 = n_states*5+1 = 81 for max 16 states. L386 ksnprintf(freqs_available+len,freq_len-len,...) uses freq_len NOT sizeof(freqs_available) as bound. 16 states 4-digit MHz: NNNN *15 + NNNN + NUL = 80+NUL=81 bytes into 80-byte buffer 1-byte BSS overrun. 5-digit MHz grows to 16 extra bytes. Init-time only BIOS-driven. Fix: enlarge to MAX_STATES*sizeof(99999 )+1 and bound ksnprintf by sizeof.

PoC verification

Evidence pack

findings/poc/DF-1962 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	357 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-1962 VERDICT

Verdict: REPRODUCED (source-confirmed)

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

Mechanism: powernow.c L343 static char freqs_available[80]. L380 freq_len=n_states(sizeof(9999 )-1)+1 = n_states5+1 = 81 for max 16 states. L386 ksnprintf(freqs_available+len,freq_len-len,...) uses freq_len NO

Citation: sys/dev/powermng/powernow/powernow.c:343-386

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: freqs_available[80] overflows for 16-state frequency list (powernow.c:343,386)

Verified recommended fix

Source-confirmed: freqs_available[80] overflows for 16-state frequency list (powernow.c:343,386)

Verdict