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[FIX] dvb: bound entry_id in CLUT parsing to prevent heap buffer overflow #2441

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[FIX] dvb: bound entry_id in CLUT parsing to prevent heap buffer overflow #2441

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acfced8
[FIX] dvb: bound entry_id in CLUT parsing to prevent heap buffer over…
Aditya-Saroha Nov 1, 2026
e63ca21
dvb: skip out-of-range CLUT entries without dropping segment
Aditya-Saroha Nov 10, 2026
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21 changes: 18 additions & 3 deletions src/lib_ccx/dvb_subtitle_decoder.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1143,6 +1143,11 @@ static int dvbsub_parse_clut_segment(void *dvb_ctx, const uint8_t *buf,
int y, cr, cb, alpha;
int r, g, b, r_add, g_add, b_add;

if (buf_size < 2)
{
return -1;
}

clut_id = *buf++;
version = ((*buf) >> 4) & 15;
buf += 1;
Expand Down Expand Up @@ -1171,7 +1176,7 @@ static int dvbsub_parse_clut_segment(void *dvb_ctx, const uint8_t *buf,

clut->version = version;

while (buf + 4 < buf_end)
while (buf + 2 <= buf_end)
{
entry_id = *buf++;

Expand All @@ -1187,13 +1192,23 @@ static int dvbsub_parse_clut_segment(void *dvb_ctx, const uint8_t *buf,

if (full_range)
{
if (buf + 4 > buf_end)
{
mprint("dvbsub_parse_clut_segment(): Truncated full_range CLUT entry\n");
return -1;
}
y = *buf++;
cr = *buf++;
cb = *buf++;
alpha = *buf++;
}
else
{
if (buf + 2 > buf_end)
{
mprint("dvbsub_parse_clut_segment(): Truncated compact CLUT entry\n");
return -1;
}
y = buf[0] & 0xfc;
cr = (((buf[0] & 3) << 2) | ((buf[1] >> 6) & 3)) << 4;
cb = (buf[1] << 2) & 0xf0;
Expand All @@ -1213,12 +1228,12 @@ static int dvbsub_parse_clut_segment(void *dvb_ctx, const uint8_t *buf,
mprint("dvbsub_parse_clut_segment(): More than one bit level marked: %x\n", depth);
}

if (depth & 0x80)
if ((depth & 0x80) && entry_id < 4)
{
clut->clut4[entry_id] = RGBA(r, g, b, 255 - alpha);
clut->ilut4[entry_id] = y;
}
else if (depth & 0x40)
else if ((depth & 0x40) && entry_id < 16)
{
clut->clut16[entry_id] = RGBA(r, g, b, 255 - alpha);
clut->ilut16[entry_id] = y;
Expand Down
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