Leahnaya/Pokemon-Gen3-to-Gen-X
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Add decompression ifdef to prevent OOB reads (disabled by default)

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Lorenzooone 2024-03-17 15:41:13 +01:00
parent 133f5a37ff
commit 4b96c30fee
1 changed files with 18 additions and 2 deletions
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20
source/decompress.s
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@ -34,9 +34,15 @@
@write way more...
#define OVERRUN_PROTECTION
@PREVENT_OOB_READS has an impact of around 2% on performance. It prevents
@the LZ77 window from going to an address before the initial destination one.
@Such LZ77 data is badly formed, and this shouldn't be enabled at all
@unless you don't trust the data coming in...
@#define PREVENT_OOB_READS
swi_LZ77UnCompWrite16bit:
swi_LZ77UnCompWrite8bit:
stmfd sp!, {r3 - r7}
stmfd sp!, {r3 - r8}
@ Read header word:
@ bit0-3: reserved
@ -51,6 +57,11 @@ swi_LZ77UnCompWrite8bit:
tst r1, #1
ldrneb r7, [r1, #-1]
#ifdef PREVENT_OOB_READS
@ Store the initial address in r8
movs r8, r1
#endif
.lz77_16bit_loop:
@ read encoder byte, shift to MSB for easier access.
ldrb r3, [r0], #1
@ -98,6 +109,11 @@ swi_LZ77UnCompWrite8bit:
movgt r4, r2
subs r2, r4
subs r5, r1, r5
#ifdef PREVENT_OOB_READS
subs r6, r5, r8
cmp r6, #0
blt .lz77_16bit_done
#endif
@ About 50% of the time, the two addresses will be aligned. Abuse this...
eor r6, r1, r5
tst r6, #1
@ -218,5 +234,5 @@ swi_LZ77UnCompWrite8bit:
orrne r7, r6, lsl #8
strneh r7, [r1, #-1]
ldmfd sp!, {r3 - r7}
ldmfd sp!, {r3 - r8}
bx lr