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Add Bounds Check to md.asm, Issue #560

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Added checks to prevent HBIOS API read/write calls from access RAM or ROM banks outside of the banks allocated for RAM/ROM disk.
This commit is contained in:
Wayne Warthen
2025-05-31 17:25:44 -07:00
parent 0d0360b277
commit 2f5cf8fce4
2 changed files with 35 additions and 1 deletions
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35
Source/HBIOS/md.asm
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@@ -359,6 +359,7 @@ MD_RDSECF: ; CALLED FROM MD_RW
; SAVE THE 4K LBA FOR FUTURE CHECKS
;
CALL MD_CALBAS ; SETUP BANK AND SECTOR
RET NZ ; RETURN IF ERROR
;
LD IX,MD_F4KBUF ; SET DESTINATION ADDRESS
LD HL,MD_FREAD_R ; PUT ROUTINE TO CALL
@@ -467,7 +468,18 @@ MD_CALBAS:
CALL PRTHEXWORD ; DISPLAY BANK AND
CALL PC_SPACE ; SECTOR RESULT
#ENDIF
;
; CHECK FOR ACCESS BEYOND AVAILABLE ROM BANKS
LD A,B ; BANK ID TO ACCUM
SUB BID_ROMD0 ; ZERO OFFSET
CP ROMD_BNKS ; CHECK FOR OUT OF BOUNDS
JR C,MD_CALBAS1 ; IF NOT, CONTINUE
LD A,ERR_IO ; ELSE SIGNAL IO ERROR
OR A ; SET FLAGS
RET ; AND RETURN
;
MD_CALBAS1:
XOR A ; SIGNAL SUCCESS
RET
;
; WRITE FLASH
@@ -485,6 +497,7 @@ MD_WRSECF: ; CALLED FROM MD_RW
LD (MD_LBA4K),BC ; SAVE 4K LBA
;
CALL MD_CALBAS ; SETUP BANK AND SECTOR
RET NZ ; RETURN ON ERROR
;
LD IX,MD_F4KBUF ; SET DESTINATION ADDRESS
LD HL,MD_FREAD_R ; PUT ROUTINE TO CALL
@@ -566,6 +579,12 @@ MD_FBAS .DW $FFFF ; BANK AND SECTOR
;
MD_RDSEC:
CALL MD_IOSETUP ; SETUP FOR MEMORY COPY
CP $FF ; ERROR?
JR NZ,MD_RDSEC1 ; IF NOT, CONTINUE
LD A,ERR_IO ; SIGNAL IO ERROR
OR A ; SET FLAGS
RET ; AND DONE
MD_RDSEC1:
#IF (MDTRACE >= 2)
LD (MD_SRC),HL
LD (MD_DST),DE
@@ -597,6 +616,12 @@ MD_RDSEC:
;
MD_WRSEC:
CALL MD_IOSETUP ; SETUP FOR MEMORY COPY
CP $FF ; ERROR?
JR NZ,MD_WRSEC1 ; IF NOT, CONTINUE
LD A,ERR_IO ; SIGNAL IO ERROR
OR A ; SET FLAGS
RET ; AND DONE
MD_WRSEC1:
EX DE,HL ; SWAP SRC/DEST FOR WRITE
#IF (MDTRACE >= 2)
LD (MD_SRC),HL
@@ -682,13 +707,21 @@ MD_IOSETUP:
JR Z,MD_IOSETUP2 ; DO ROM DRIVE, ELSE FALL THRU FOR RAM DRIVE
;
MD_IOSETUP1: ; ROM
CP ROMD_BNKS ; WITHIN AVAILABLE ROM DISK BANKS?
JR NC,MD_IOSETUP3 ; HANDLE OUT OF BOUNDS
ADD A,BID_ROMD0
RET
;
MD_IOSETUP2: ; RAM
CP RAMD_BNKS ; WITHIN AVAILABLE ROM DISK BANKS?
JR NC,MD_IOSETUP3 ; HANDLE OUT OF BOUNDS
ADD A,BID_RAMD0
RET
;
MD_IOSETUP3:
OR $FF ; SIGNAL ERROR
RET ; DONE
;
;
;
#IF (MDTRACE >= 2)