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target/mips/mxu: Avoid overrun in gen_mxu_q8adde() 

Coverity reports a potential overruns (CID 1517770):

  Overrunning array "mxu_gpr" of 15 8-byte elements at
  element index 4294967295 (byte offset 34359738367)
  using index "XRb - 1U" (which evaluates to 4294967295).

Add a gen_extract_mxu_gpr() helper similar to
gen_load_mxu_gpr() to safely extract MXU registers.

Fixes: eb79951ab6 ("target/mips/mxu: Add Q8ADDE ... insns")
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230712060806.82323-4-philmd@linaro.org>
This commit is contained in:
Philippe Mathieu-Daudé 2023-07-12 07:41:32 +02:00
parent e37fdc7381
commit fb51df0c8e
1 changed files with 18 additions and 8 deletions
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26
target/mips/tcg/mxu_translate.c
View File

@ -644,6 +644,16 @@ static inline void gen_store_mxu_gpr(TCGv t, unsigned int reg)
}
}
static inline void gen_extract_mxu_gpr(TCGv t, unsigned int reg,
unsigned int ofs, unsigned int len)
{
if (reg == 0) {
tcg_gen_movi_tl(t, 0);
} else if (reg <= 15) {
tcg_gen_extract_tl(t, mxu_gpr[reg - 1], ofs, len);
}
}
/* MXU control register moves. */
static inline void gen_load_mxu_cr(TCGv t)
{
@ -3004,10 +3014,10 @@ static void gen_mxu_q8adde(DisasContext *ctx, bool accumulate)
TCGv t5 = tcg_temp_new();
if (XRa != 0) {
tcg_gen_extract_tl(t0, mxu_gpr[XRb - 1], 16, 8);
tcg_gen_extract_tl(t1, mxu_gpr[XRc - 1], 16, 8);
tcg_gen_extract_tl(t2, mxu_gpr[XRb - 1], 24, 8);
tcg_gen_extract_tl(t3, mxu_gpr[XRc - 1], 24, 8);
gen_extract_mxu_gpr(t0, XRb, 16, 8);
gen_extract_mxu_gpr(t1, XRc, 16, 8);
gen_extract_mxu_gpr(t2, XRb, 24, 8);
gen_extract_mxu_gpr(t3, XRc, 24, 8);
if (aptn2 & 2) {
tcg_gen_sub_tl(t0, t0, t1);
tcg_gen_sub_tl(t2, t2, t3);
@ -3027,10 +3037,10 @@ static void gen_mxu_q8adde(DisasContext *ctx, bool accumulate)
tcg_gen_or_tl(t4, t2, t0);
}
if (XRd != 0) {
tcg_gen_extract_tl(t0, mxu_gpr[XRb - 1], 0, 8);
tcg_gen_extract_tl(t1, mxu_gpr[XRc - 1], 0, 8);
tcg_gen_extract_tl(t2, mxu_gpr[XRb - 1], 8, 8);
tcg_gen_extract_tl(t3, mxu_gpr[XRc - 1], 8, 8);
gen_extract_mxu_gpr(t0, XRb, 0, 8);
gen_extract_mxu_gpr(t1, XRc, 0, 8);
gen_extract_mxu_gpr(t2, XRb, 8, 8);
gen_extract_mxu_gpr(t3, XRc, 8, 8);
if (aptn2 & 1) {
tcg_gen_sub_tl(t0, t0, t1);
tcg_gen_sub_tl(t2, t2, t3);