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Fix shift-exponent UB in PGX decoder #427

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Fix shift-exponent UB in PGX decoder #427

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9 changes: 5 additions & 4 deletions src/libjasper/pgx/pgx_dec.c
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Original file line number Diff line number Diff line change
Expand Up @@ -299,7 +299,7 @@ static int pgx_gethdr(jas_stream_t *in, pgx_hdr_t *hdr)
jas_logerrorf("cannot get height\n");
goto error;
}
if (hdr->prec > 32) {
if (hdr->prec < 1 || hdr->prec > 32) {
jas_logerrorf("unsupported precision (%d)\n", hdr->prec);
goto error;
}
Expand Down Expand Up @@ -369,7 +369,7 @@ static int_fast32_t pgx_getword(jas_stream_t *in, bool bigendian, int prec)
j = bigendian ? (wordsize - 1 - i) : i;
val = val | ((c & 0xffU) << (8 * j));
}
val &= (JAS_CAST(uint_fast32_t, 1) << prec) - 1;
val &= (JAS_CAST(uint_fast64_t, 1) << prec) - 1;
return val;

error:
Expand Down Expand Up @@ -524,7 +524,8 @@ static int pgx_getuint32(jas_stream_t *in, uint_fast32_t *val)
static jas_seqent_t pgx_wordtoint(uint_fast32_t v, int prec, bool sgnd)
{
jas_seqent_t ret;
v &= (1 << prec) - 1;
ret = (sgnd && (v & (1 << (prec - 1)))) ? (v - (1 << prec)) : v;
v &= JAS_CAST(uint_fast32_t, JAS_POW2_X(uint_fast64_t, prec) - 1);
ret = (sgnd && (v & JAS_POW2_X(uint_fast32_t, prec - 1))) ?
JAS_CAST(jas_seqent_t, v) - JAS_POW2_X(jas_seqent_t, prec) : v;
return ret;
}