| Message ID | 20210901141008.17203-1-peter.maydell@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] target/i386: Use assert() to sanity-check b1 in SSE decode | expand |
On 9/1/21 4:10 PM, Peter Maydell wrote: > In the SSE decode function gen_sse(), we combine a byte > 'b' and a value 'b1' which can be [0..3], and switch on them: > b |= (b1 << 8); > switch (b) { > ... > default: > unknown_op: > gen_unknown_opcode(env, s); > return; > } > > In three cases inside this switch, we were then also checking for > "if (b1 >= 2) { goto unknown_op; }". > However, this can never happen, because the 'case' values in each place > are 0x0nn or 0x1nn and the switch will have directed the b1 == (2, 3) > cases to the default already. > > This check was added in commit c045af25a52e9 in 2010; the added code > was unnecessary then as well, and was apparently intended only to > ensure that we never accidentally ended up indexing off the end > of an sse_op_table with only 2 entries as a result of future bugs > in the decode logic. > > Change the checks to assert() instead, and make sure they're always > immediately before the array access they are protecting. > > Fixes: Coverity CID 1460207 > Signed-off-by: Peter Maydell<peter.maydell@linaro.org> > --- > v1->v2: use assert() rather than just deleting the if()s Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
Ping? (this has been reviewed) thanks -- PMM On Wed, 1 Sept 2021 at 15:10, Peter Maydell <peter.maydell@linaro.org> wrote: > > In the SSE decode function gen_sse(), we combine a byte > 'b' and a value 'b1' which can be [0..3], and switch on them: > b |= (b1 << 8); > switch (b) { > ... > default: > unknown_op: > gen_unknown_opcode(env, s); > return; > } > > In three cases inside this switch, we were then also checking for > "if (b1 >= 2) { goto unknown_op; }". > However, this can never happen, because the 'case' values in each place > are 0x0nn or 0x1nn and the switch will have directed the b1 == (2, 3) > cases to the default already. > > This check was added in commit c045af25a52e9 in 2010; the added code > was unnecessary then as well, and was apparently intended only to > ensure that we never accidentally ended up indexing off the end > of an sse_op_table with only 2 entries as a result of future bugs > in the decode logic. > > Change the checks to assert() instead, and make sure they're always > immediately before the array access they are protecting. > > Fixes: Coverity CID 1460207 > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> > --- > v1->v2: use assert() rather than just deleting the if()s > > target/i386/tcg/translate.c | 12 +++--------- > 1 file changed, 3 insertions(+), 9 deletions(-) > > diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c > index aacb605eee4..a4fee5e445d 100644 > --- a/target/i386/tcg/translate.c > +++ b/target/i386/tcg/translate.c > @@ -3521,9 +3521,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > case 0x171: /* shift xmm, im */ > case 0x172: > case 0x173: > - if (b1 >= 2) { > - goto unknown_op; > - } > val = x86_ldub_code(env, s); > if (is_xmm) { > tcg_gen_movi_tl(s->T0, val); > @@ -3542,6 +3539,7 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > offsetof(CPUX86State, mmx_t0.MMX_L(1))); > op1_offset = offsetof(CPUX86State,mmx_t0); > } > + assert(b1 < 2); > sse_fn_epp = sse_op_table2[((b - 1) & 3) * 8 + > (((modrm >> 3)) & 7)][b1]; > if (!sse_fn_epp) { > @@ -3772,10 +3770,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > rm = modrm & 7; > reg = ((modrm >> 3) & 7) | REX_R(s); > mod = (modrm >> 6) & 3; > - if (b1 >= 2) { > - goto unknown_op; > - } > > + assert(b1 < 2); > sse_fn_epp = sse_op_table6[b].op[b1]; > if (!sse_fn_epp) { > goto unknown_op; > @@ -4202,10 +4198,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > rm = modrm & 7; > reg = ((modrm >> 3) & 7) | REX_R(s); > mod = (modrm >> 6) & 3; > - if (b1 >= 2) { > - goto unknown_op; > - } > > + assert(b1 < 2); > sse_fn_eppi = sse_op_table7[b].op[b1]; > if (!sse_fn_eppi) { > goto unknown_op; > -- > 2.20.1
Ping^2 ! thanks -- PMM On Mon, 13 Sept 2021 at 13:34, Peter Maydell <peter.maydell@linaro.org> wrote: > > Ping? (this has been reviewed) > > thanks > -- PMM > > On Wed, 1 Sept 2021 at 15:10, Peter Maydell <peter.maydell@linaro.org> wrote: > > > > In the SSE decode function gen_sse(), we combine a byte > > 'b' and a value 'b1' which can be [0..3], and switch on them: > > b |= (b1 << 8); > > switch (b) { > > ... > > default: > > unknown_op: > > gen_unknown_opcode(env, s); > > return; > > } > > > > In three cases inside this switch, we were then also checking for > > "if (b1 >= 2) { goto unknown_op; }". > > However, this can never happen, because the 'case' values in each place > > are 0x0nn or 0x1nn and the switch will have directed the b1 == (2, 3) > > cases to the default already. > > > > This check was added in commit c045af25a52e9 in 2010; the added code > > was unnecessary then as well, and was apparently intended only to > > ensure that we never accidentally ended up indexing off the end > > of an sse_op_table with only 2 entries as a result of future bugs > > in the decode logic. > > > > Change the checks to assert() instead, and make sure they're always > > immediately before the array access they are protecting. > > > > Fixes: Coverity CID 1460207 > > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> > > --- > > v1->v2: use assert() rather than just deleting the if()s > > > > target/i386/tcg/translate.c | 12 +++--------- > > 1 file changed, 3 insertions(+), 9 deletions(-) > > > > diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c > > index aacb605eee4..a4fee5e445d 100644 > > --- a/target/i386/tcg/translate.c > > +++ b/target/i386/tcg/translate.c > > @@ -3521,9 +3521,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > case 0x171: /* shift xmm, im */ > > case 0x172: > > case 0x173: > > - if (b1 >= 2) { > > - goto unknown_op; > > - } > > val = x86_ldub_code(env, s); > > if (is_xmm) { > > tcg_gen_movi_tl(s->T0, val); > > @@ -3542,6 +3539,7 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > offsetof(CPUX86State, mmx_t0.MMX_L(1))); > > op1_offset = offsetof(CPUX86State,mmx_t0); > > } > > + assert(b1 < 2); > > sse_fn_epp = sse_op_table2[((b - 1) & 3) * 8 + > > (((modrm >> 3)) & 7)][b1]; > > if (!sse_fn_epp) { > > @@ -3772,10 +3770,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > rm = modrm & 7; > > reg = ((modrm >> 3) & 7) | REX_R(s); > > mod = (modrm >> 6) & 3; > > - if (b1 >= 2) { > > - goto unknown_op; > > - } > > > > + assert(b1 < 2); > > sse_fn_epp = sse_op_table6[b].op[b1]; > > if (!sse_fn_epp) { > > goto unknown_op; > > @@ -4202,10 +4198,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > rm = modrm & 7; > > reg = ((modrm >> 3) & 7) | REX_R(s); > > mod = (modrm >> 6) & 3; > > - if (b1 >= 2) { > > - goto unknown_op; > > - } > > > > + assert(b1 < 2); > > sse_fn_eppi = sse_op_table7[b].op[b1]; > > if (!sse_fn_eppi) { > > goto unknown_op; > > -- > > 2.20.1
Ping^3, now 2 months after patch posted and reviewed... -- PMM On Mon, 27 Sept 2021 at 11:03, Peter Maydell <peter.maydell@linaro.org> wrote: > > Ping^2 ! > > thanks > -- PMM > > On Mon, 13 Sept 2021 at 13:34, Peter Maydell <peter.maydell@linaro.org> wrote: > > > > Ping? (this has been reviewed) > > > > thanks > > -- PMM > > > > On Wed, 1 Sept 2021 at 15:10, Peter Maydell <peter.maydell@linaro.org> wrote: > > > > > > In the SSE decode function gen_sse(), we combine a byte > > > 'b' and a value 'b1' which can be [0..3], and switch on them: > > > b |= (b1 << 8); > > > switch (b) { > > > ... > > > default: > > > unknown_op: > > > gen_unknown_opcode(env, s); > > > return; > > > } > > > > > > In three cases inside this switch, we were then also checking for > > > "if (b1 >= 2) { goto unknown_op; }". > > > However, this can never happen, because the 'case' values in each place > > > are 0x0nn or 0x1nn and the switch will have directed the b1 == (2, 3) > > > cases to the default already. > > > > > > This check was added in commit c045af25a52e9 in 2010; the added code > > > was unnecessary then as well, and was apparently intended only to > > > ensure that we never accidentally ended up indexing off the end > > > of an sse_op_table with only 2 entries as a result of future bugs > > > in the decode logic. > > > > > > Change the checks to assert() instead, and make sure they're always > > > immediately before the array access they are protecting. > > > > > > Fixes: Coverity CID 1460207 > > > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> > > > --- > > > v1->v2: use assert() rather than just deleting the if()s > > > > > > target/i386/tcg/translate.c | 12 +++--------- > > > 1 file changed, 3 insertions(+), 9 deletions(-) > > > > > > diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c > > > index aacb605eee4..a4fee5e445d 100644 > > > --- a/target/i386/tcg/translate.c > > > +++ b/target/i386/tcg/translate.c > > > @@ -3521,9 +3521,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > case 0x171: /* shift xmm, im */ > > > case 0x172: > > > case 0x173: > > > - if (b1 >= 2) { > > > - goto unknown_op; > > > - } > > > val = x86_ldub_code(env, s); > > > if (is_xmm) { > > > tcg_gen_movi_tl(s->T0, val); > > > @@ -3542,6 +3539,7 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > offsetof(CPUX86State, mmx_t0.MMX_L(1))); > > > op1_offset = offsetof(CPUX86State,mmx_t0); > > > } > > > + assert(b1 < 2); > > > sse_fn_epp = sse_op_table2[((b - 1) & 3) * 8 + > > > (((modrm >> 3)) & 7)][b1]; > > > if (!sse_fn_epp) { > > > @@ -3772,10 +3770,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > rm = modrm & 7; > > > reg = ((modrm >> 3) & 7) | REX_R(s); > > > mod = (modrm >> 6) & 3; > > > - if (b1 >= 2) { > > > - goto unknown_op; > > > - } > > > > > > + assert(b1 < 2); > > > sse_fn_epp = sse_op_table6[b].op[b1]; > > > if (!sse_fn_epp) { > > > goto unknown_op; > > > @@ -4202,10 +4198,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > rm = modrm & 7; > > > reg = ((modrm >> 3) & 7) | REX_R(s); > > > mod = (modrm >> 6) & 3; > > > - if (b1 >= 2) { > > > - goto unknown_op; > > > - } > > > > > > + assert(b1 < 2); > > > sse_fn_eppi = sse_op_table7[b].op[b1]; > > > if (!sse_fn_eppi) { > > > goto unknown_op; > > > -- > > > 2.20.1
Ping^4. Who is collecting target/i386 patches these days ? -- PMM On Mon, 1 Nov 2021 at 16:18, Peter Maydell <peter.maydell@linaro.org> wrote: > > Ping^3, now 2 months after patch posted and reviewed... > > -- PMM > > On Mon, 27 Sept 2021 at 11:03, Peter Maydell <peter.maydell@linaro.org> wrote: > > > > Ping^2 ! > > > > thanks > > -- PMM > > > > On Mon, 13 Sept 2021 at 13:34, Peter Maydell <peter.maydell@linaro.org> wrote: > > > > > > Ping? (this has been reviewed) > > > > > > thanks > > > -- PMM > > > > > > On Wed, 1 Sept 2021 at 15:10, Peter Maydell <peter.maydell@linaro.org> wrote: > > > > > > > > In the SSE decode function gen_sse(), we combine a byte > > > > 'b' and a value 'b1' which can be [0..3], and switch on them: > > > > b |= (b1 << 8); > > > > switch (b) { > > > > ... > > > > default: > > > > unknown_op: > > > > gen_unknown_opcode(env, s); > > > > return; > > > > } > > > > > > > > In three cases inside this switch, we were then also checking for > > > > "if (b1 >= 2) { goto unknown_op; }". > > > > However, this can never happen, because the 'case' values in each place > > > > are 0x0nn or 0x1nn and the switch will have directed the b1 == (2, 3) > > > > cases to the default already. > > > > > > > > This check was added in commit c045af25a52e9 in 2010; the added code > > > > was unnecessary then as well, and was apparently intended only to > > > > ensure that we never accidentally ended up indexing off the end > > > > of an sse_op_table with only 2 entries as a result of future bugs > > > > in the decode logic. > > > > > > > > Change the checks to assert() instead, and make sure they're always > > > > immediately before the array access they are protecting. > > > > > > > > Fixes: Coverity CID 1460207 > > > > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> > > > > --- > > > > v1->v2: use assert() rather than just deleting the if()s > > > > > > > > target/i386/tcg/translate.c | 12 +++--------- > > > > 1 file changed, 3 insertions(+), 9 deletions(-) > > > > > > > > diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c > > > > index aacb605eee4..a4fee5e445d 100644 > > > > --- a/target/i386/tcg/translate.c > > > > +++ b/target/i386/tcg/translate.c > > > > @@ -3521,9 +3521,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > > case 0x171: /* shift xmm, im */ > > > > case 0x172: > > > > case 0x173: > > > > - if (b1 >= 2) { > > > > - goto unknown_op; > > > > - } > > > > val = x86_ldub_code(env, s); > > > > if (is_xmm) { > > > > tcg_gen_movi_tl(s->T0, val); > > > > @@ -3542,6 +3539,7 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > > offsetof(CPUX86State, mmx_t0.MMX_L(1))); > > > > op1_offset = offsetof(CPUX86State,mmx_t0); > > > > } > > > > + assert(b1 < 2); > > > > sse_fn_epp = sse_op_table2[((b - 1) & 3) * 8 + > > > > (((modrm >> 3)) & 7)][b1]; > > > > if (!sse_fn_epp) { > > > > @@ -3772,10 +3770,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > > rm = modrm & 7; > > > > reg = ((modrm >> 3) & 7) | REX_R(s); > > > > mod = (modrm >> 6) & 3; > > > > - if (b1 >= 2) { > > > > - goto unknown_op; > > > > - } > > > > > > > > + assert(b1 < 2); > > > > sse_fn_epp = sse_op_table6[b].op[b1]; > > > > if (!sse_fn_epp) { > > > > goto unknown_op; > > > > @@ -4202,10 +4198,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > > rm = modrm & 7; > > > > reg = ((modrm >> 3) & 7) | REX_R(s); > > > > mod = (modrm >> 6) & 3; > > > > - if (b1 >= 2) { > > > > - goto unknown_op; > > > > - } > > > > > > > > + assert(b1 < 2); > > > > sse_fn_eppi = sse_op_table7[b].op[b1]; > > > > if (!sse_fn_eppi) { > > > > goto unknown_op; > > > > -- > > > > 2.20.1
Gave up pinging for i386 maintainers; will take this via target-arm.next. thanks -- PMM On Mon, 15 Nov 2021 at 14:38, Peter Maydell <peter.maydell@linaro.org> wrote: > > Ping^4. Who is collecting target/i386 patches these days ? > > -- PMM > > On Mon, 1 Nov 2021 at 16:18, Peter Maydell <peter.maydell@linaro.org> wrote: > > > > Ping^3, now 2 months after patch posted and reviewed... > > > > -- PMM > > > > On Mon, 27 Sept 2021 at 11:03, Peter Maydell <peter.maydell@linaro.org> wrote: > > > > > > Ping^2 ! > > > > > > thanks > > > -- PMM > > > > > > On Mon, 13 Sept 2021 at 13:34, Peter Maydell <peter.maydell@linaro.org> wrote: > > > > > > > > Ping? (this has been reviewed) > > > > > > > > thanks > > > > -- PMM > > > > > > > > On Wed, 1 Sept 2021 at 15:10, Peter Maydell <peter.maydell@linaro.org> wrote: > > > > > > > > > > In the SSE decode function gen_sse(), we combine a byte > > > > > 'b' and a value 'b1' which can be [0..3], and switch on them: > > > > > b |= (b1 << 8); > > > > > switch (b) { > > > > > ... > > > > > default: > > > > > unknown_op: > > > > > gen_unknown_opcode(env, s); > > > > > return; > > > > > } > > > > > > > > > > In three cases inside this switch, we were then also checking for > > > > > "if (b1 >= 2) { goto unknown_op; }". > > > > > However, this can never happen, because the 'case' values in each place > > > > > are 0x0nn or 0x1nn and the switch will have directed the b1 == (2, 3) > > > > > cases to the default already. > > > > > > > > > > This check was added in commit c045af25a52e9 in 2010; the added code > > > > > was unnecessary then as well, and was apparently intended only to > > > > > ensure that we never accidentally ended up indexing off the end > > > > > of an sse_op_table with only 2 entries as a result of future bugs > > > > > in the decode logic. > > > > > > > > > > Change the checks to assert() instead, and make sure they're always > > > > > immediately before the array access they are protecting. > > > > > > > > > > Fixes: Coverity CID 1460207 > > > > > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> > > > > > --- > > > > > v1->v2: use assert() rather than just deleting the if()s > > > > > > > > > > target/i386/tcg/translate.c | 12 +++--------- > > > > > 1 file changed, 3 insertions(+), 9 deletions(-) > > > > > > > > > > diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c > > > > > index aacb605eee4..a4fee5e445d 100644 > > > > > --- a/target/i386/tcg/translate.c > > > > > +++ b/target/i386/tcg/translate.c > > > > > @@ -3521,9 +3521,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > > > case 0x171: /* shift xmm, im */ > > > > > case 0x172: > > > > > case 0x173: > > > > > - if (b1 >= 2) { > > > > > - goto unknown_op; > > > > > - } > > > > > val = x86_ldub_code(env, s); > > > > > if (is_xmm) { > > > > > tcg_gen_movi_tl(s->T0, val); > > > > > @@ -3542,6 +3539,7 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > > > offsetof(CPUX86State, mmx_t0.MMX_L(1))); > > > > > op1_offset = offsetof(CPUX86State,mmx_t0); > > > > > } > > > > > + assert(b1 < 2); > > > > > sse_fn_epp = sse_op_table2[((b - 1) & 3) * 8 + > > > > > (((modrm >> 3)) & 7)][b1]; > > > > > if (!sse_fn_epp) { > > > > > @@ -3772,10 +3770,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > > > rm = modrm & 7; > > > > > reg = ((modrm >> 3) & 7) | REX_R(s); > > > > > mod = (modrm >> 6) & 3; > > > > > - if (b1 >= 2) { > > > > > - goto unknown_op; > > > > > - } > > > > > > > > > > + assert(b1 < 2); > > > > > sse_fn_epp = sse_op_table6[b].op[b1]; > > > > > if (!sse_fn_epp) { > > > > > goto unknown_op; > > > > > @@ -4202,10 +4198,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, > > > > > rm = modrm & 7; > > > > > reg = ((modrm >> 3) & 7) | REX_R(s); > > > > > mod = (modrm >> 6) & 3; > > > > > - if (b1 >= 2) { > > > > > - goto unknown_op; > > > > > - } > > > > > > > > > > + assert(b1 < 2); > > > > > sse_fn_eppi = sse_op_table7[b].op[b1]; > > > > > if (!sse_fn_eppi) { > > > > > goto unknown_op; > > > > > -- > > > > > 2.20.1
diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c index aacb605eee4..a4fee5e445d 100644 --- a/target/i386/tcg/translate.c +++ b/target/i386/tcg/translate.c @@ -3521,9 +3521,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, case 0x171: /* shift xmm, im */ case 0x172: case 0x173: - if (b1 >= 2) { - goto unknown_op; - } val = x86_ldub_code(env, s); if (is_xmm) { tcg_gen_movi_tl(s->T0, val); @@ -3542,6 +3539,7 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, offsetof(CPUX86State, mmx_t0.MMX_L(1))); op1_offset = offsetof(CPUX86State,mmx_t0); } + assert(b1 < 2); sse_fn_epp = sse_op_table2[((b - 1) & 3) * 8 + (((modrm >> 3)) & 7)][b1]; if (!sse_fn_epp) { @@ -3772,10 +3770,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, rm = modrm & 7; reg = ((modrm >> 3) & 7) | REX_R(s); mod = (modrm >> 6) & 3; - if (b1 >= 2) { - goto unknown_op; - } + assert(b1 < 2); sse_fn_epp = sse_op_table6[b].op[b1]; if (!sse_fn_epp) { goto unknown_op; @@ -4202,10 +4198,8 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, rm = modrm & 7; reg = ((modrm >> 3) & 7) | REX_R(s); mod = (modrm >> 6) & 3; - if (b1 >= 2) { - goto unknown_op; - } + assert(b1 < 2); sse_fn_eppi = sse_op_table7[b].op[b1]; if (!sse_fn_eppi) { goto unknown_op;
In the SSE decode function gen_sse(), we combine a byte 'b' and a value 'b1' which can be [0..3], and switch on them: b |= (b1 << 8); switch (b) { ... default: unknown_op: gen_unknown_opcode(env, s); return; } In three cases inside this switch, we were then also checking for "if (b1 >= 2) { goto unknown_op; }". However, this can never happen, because the 'case' values in each place are 0x0nn or 0x1nn and the switch will have directed the b1 == (2, 3) cases to the default already. This check was added in commit c045af25a52e9 in 2010; the added code was unnecessary then as well, and was apparently intended only to ensure that we never accidentally ended up indexing off the end of an sse_op_table with only 2 entries as a result of future bugs in the decode logic. Change the checks to assert() instead, and make sure they're always immediately before the array access they are protecting. Fixes: Coverity CID 1460207 Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- v1->v2: use assert() rather than just deleting the if()s target/i386/tcg/translate.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-)