Skip to content

scsi: reject truncated MODE SELECT parameter lists #404

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
erichelgeson wants to merge 1 commit into
base: main
Choose a base branch
from
Open

scsi: reject truncated MODE SELECT parameter lists #404

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
23 changes: 22 additions & 1 deletion lib/SCSI2SD/src/firmware/mode.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
// Copyright (C) 2019 Landon Rodgers <g.landon.rodgers@gmail.com>
// Copyright (c) 2024-2025 Rabbit Hole Computing™
// Copyright (C) 2024 jokker <jokker@gmail.com>
// Copyright (c) 2026 Eric Helgeson <eric@bluescsi.com>
// This file is part of SCSI2SD.
//
// SCSI2SD is free software: you can redistribute it and/or modify
Expand Down Expand Up @@ -679,6 +680,13 @@ static void doModeSelect(void)

int idx;
int blockDescLen;

// SCSI2 8.2.8: the command shall be terminated with CHECK CONDITION
// if the parameter list length truncates the mode parameter header,
// the block descriptor(s), or a mode page.
int headerLen = (scsiDev.cdb[0] == 0x55) ? 8 : 4;
if (scsiDev.dataLen < headerLen) goto badLength;

if (scsiDev.cdb[0] == 0x55)
{
blockDescLen =
Expand All @@ -691,6 +699,9 @@ static void doModeSelect(void)
idx = 4;
}

// The header check above guarantees dataLen >= idx.
if (blockDescLen > scsiDev.dataLen - idx) goto badLength;

// The unwritten rule. Blocksizes are normally set using the
// block descriptor value, not by changing page 0x03.
if (blockDescLen >= 8)
Expand Down Expand Up @@ -724,8 +735,9 @@ static void doModeSelect(void)
int pageCode = scsiDev.data[idx] & 0x3F;
if (pageCode == 0) goto out;

if (idx + 2 > scsiDev.dataLen) goto badLength;
int pageLen = scsiDev.data[idx + 1];
if (idx + 2 + pageLen > scsiDev.dataLen) goto bad;
if (idx + 2 + pageLen > scsiDev.dataLen) goto badLength;

switch (pageCode)
{
Expand Down Expand Up @@ -767,6 +779,15 @@ static void doModeSelect(void)
}

goto out;

// SCSI2 8.2.8 separates a parameter list that is too short for what it
// describes (1Ah) from one whose contents are unsupported (26h).
badLength:
scsiDev.status = CHECK_CONDITION;
scsiDev.target->sense.code = ILLEGAL_REQUEST;
scsiDev.target->sense.asc = PARAMETER_LIST_LENGTH_ERROR;
goto out;

bad:
scsiDev.status = CHECK_CONDITION;
scsiDev.target->sense.code = ILLEGAL_REQUEST;
Expand Down