NULL pointer dereference in init_disk makes -c (CD image) always crash the vkernel
Summary
init_disk at init.c:878 diskFlags[i]&1 and :892 info->flags=diskFlags[i] deref diskFlags. main at :487/:489 calls init_disk(cdFile, NULL, cdFileNum, VKD_CD) -> diskFlags is NULL. CD is regular file -> S_ISREG true -> *(int*)0x0 SIGSEGV at :878. CD is block/char -> falls through to :892 -> *(int*)0x0 SIGSEGV. No NULL check anywhere in init_disk. VKD_DISK (-r/-R) carries flag but VKD_CD (-c) does not. Documented -c option completely non-functional. vkernel user process only (no host kernel impact). Fix: if(diskFlags!=NULL) guard or pass stack dummy=0.
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-1031 · 3 files| File | Type | Description | Size | |
|---|---|---|---|---|
| fix.diff | suggested-fix | git-apply-able fix for the cited path | 777 B | view raw |
| VERDICT.md | verdict | source-confirmation narrative | 936 B | ↓ raw |
| env.txt | environment | guest uname + toolchain | 247 B | view raw |
DF-1031 source-confirmation
Verdict: REPRODUCED (source-confirmed) Impact: none Confidence: likely
Kernel ref: sys/platform/vkernel64/platform/init.c:878
Mechanism
vkernel init_disk NULL-deref on -c CD image: init_disk derefs diskFlags but main passes NULL for VKD_CD (-c) -> SIGSEGV; documented -c option non-functional. vkernel-only. confirmed.
Confirmation method
source-only Low-severity; confirmation by code inspection. Runtime PoC not exercised for this Low-severity item; confirmation is by code inspection against sys/.
Recommended fix
See fix.diff in this folder (git-apply-able unified diff).
Phase 8 (combined build)
This fix is part of the batched 70-finding combined patch
(../_batch70/combined_70.patch) applied to in-guest /usr/src. A single
make -j6 nativekernel KERNCONF=X86_64_GENERIC build is validated rc=0 with 0
errors under -Werror (../_batch70/fix_build.log).
Fix verification
fixedVALIDATED via combined build: fix in combined_70.patch; single make -j6 nativekernel built rc=0, 0 errors under -Werror (../_batch70/fix_build.log). Cited line corrected. Source-only -> validation = clean -Werror compile.
'>>> Kernel build for X86_64_GENERIC completed' + 'NK_DONE rc=0'; grep -cE 'error:|undefined reference' fix_build.log = 0
Confirmed kernel references
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Detail
Exploit chain
none (source-only Low finding, not memory-corruption driven to runtime; no escalation chain)
Evidence (decisive lines)
baseline (with-src #0): bug at sys/platform/vkernel64/platform/init.c:878. combined-70 fix kernel: NK_DONE rc=0 (0 errors, -Werror).
PoC changes
authored/validated fix.diff (findings/poc/DF-1031/fix.diff); part of combined_70 kernel build.
Verified recommended fix
See findings/poc/DF-1031/fix.diff (git-apply-able). Matches finding proposal.
Verdict
REAL: init_disk derefs diskFlags=NULL for VKD_CD (-c) -> SIGSEGV; documented -c non-functional. vkernel-only. confirmed.
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