Re: [PATCH v2] ACPI/IORT: Fix GCC 12 warning

Joe Perches
2022-02-12T05:03:40Z

On Fri, 2022-02-11 at 16:37 -0800, Kees Cook wrote:
[]
> Well, I'm for #1, though perhaps with a more narrow view: some semantics
> are just weird/surprising. ;) Until I first encountered this warning a
> few years ago when working on GCC_PLUGIN_STRUCTLEAK_BYREF_ALL, I didn't
> even know putting declarations there was valid C. ;)
>
> Whack-a-mole is part of the work to make these kinds of treewide
> changes, but the hope is to find as much of it ahead of time as
> possible. And, no, I have no interest in security theater. (Not
> everything has equal levels of effectiveness, of course, but I don't
> think that's what you're saying.)
>
> > In fairness I'd have no objection to that patch if it came with a convincing
> > justification, but that is so far very much lacking. My aim here is not to
> > be a change-averse Luddite, but to try to find a compromise where I can
> > actually have some confidence in such changes being made. Let's not start
> > pretending that 3 100ml bottles of shampoo are somehow "safer" than a 300ml
> > bottle of shampoo...
>
> Sure. I think I am trying to take a pragmatic approach here, which is
> that gaining auto-var-init is a big deal (killing entire classes of
> vulnerabilities), but it comes with an annoying compiler bug (that we do
> get a warning about) for an uncommon code pattern that is easy to fix.
> So rather than delaying the defense until the sharp edge on the compiler
> gets fixed, I'd like to get the rest rolling while the edge is filed.

coccinelle would probably find most all of them.

$ cat switch_define.cocci
@@
expression e;
type t;
identifier i;
@@

switch (e) {
* t i;
}

$ spatch --very-quiet -sp-file switch_define.cocci .
13831 files match
diff -u -p ./arch/arc/kernel/unwind.c /tmp/nothing/arch/arc/kernel/unwind.c
--- ./arch/arc/kernel/unwind.c
+++ /tmp/nothing/arch/arc/kernel/unwind.c
@@ -718,7 +718,6 @@ static int processCFI(const u8 *start, c
}
for (ptr.p8 = start; result && ptr.p8 < end;) {
switch (*ptr.p8 >> 6) {
- uleb128_t value;

case 0:
opcode = *ptr.p8++;
diff -u -p ./arch/arm/kernel/module-plts.c /tmp/nothing/arch/arm/kernel/module-plts.c
--- ./arch/arm/kernel/module-plts.c
+++ /tmp/nothing/arch/arm/kernel/module-plts.c
@@ -124,7 +124,6 @@ static bool is_zero_addend_relocation(El
* PC bias into account, i.e., -8 for ARM and -4 for Thumb2.
*/
switch (ELF32_R_TYPE(rel->r_info)) {
- u16 upper, lower;

case R_ARM_THM_CALL:
case R_ARM_THM_JUMP24:
diff -u -p ./arch/mips/mti-malta/malta-init.c /tmp/nothing/arch/mips/mti-malta/malta-init.c
--- ./arch/mips/mti-malta/malta-init.c
+++ /tmp/nothing/arch/mips/mti-malta/malta-init.c
@@ -168,7 +168,6 @@ void __init prom_init(void)
}

switch (mips_revision_sconid) {
- u32 start, map, mask, data;

case MIPS_REVISION_SCON_GT64120:
/*
diff -u -p ./arch/parisc/kernel/inventory.c /tmp/nothing/arch/parisc/kernel/inventory.c
--- ./arch/parisc/kernel/inventory.c
+++ /tmp/nothing/arch/parisc/kernel/inventory.c
@@ -235,7 +235,6 @@ pat_query_module(ulong pcell_loc, ulong
#ifdef DEBUG_PAT
/* dump what we see so far... */
switch (PAT_GET_ENTITY(dev->mod_info)) {
- pdc_pat_cell_mod_maddr_block_t io_pdc_cell;
unsigned long i;

case PAT_ENTITY_PROC:
diff -u -p ./arch/powerpc/xmon/xmon.c /tmp/nothing/arch/powerpc/xmon/xmon.c
--- ./arch/powerpc/xmon/xmon.c
+++ /tmp/nothing/arch/powerpc/xmon/xmon.c
@@ -1528,7 +1528,6 @@ bpt_cmds(void)
cmd = inchar();

switch (cmd) {
- static const char badaddr[] = "Only kernel addresses are permitted for breakpoints\n";
int mode;
case 'd': /* bd - hardware data breakpoint */
if (xmon_is_ro) {
diff -u -p ./arch/um/drivers/ubd_kern.c /tmp/nothing/arch/um/drivers/ubd_kern.c
--- ./arch/um/drivers/ubd_kern.c
+++ /tmp/nothing/arch/um/drivers/ubd_kern.c
@@ -1407,7 +1407,6 @@ static int ubd_ioctl(struct block_device
u16 ubd_id[ATA_ID_WORDS];

switch (cmd) {
- struct cdrom_volctrl volume;
case HDIO_GET_IDENTITY:
memset(&ubd_id, 0, ATA_ID_WORDS * 2);
ubd_id[ATA_ID_CYLS] = ubd_dev->size / (128 * 32 * 512);
diff -u -p ./arch/x86/kernel/cpu/cyrix.c /tmp/nothing/arch/x86/kernel/cpu/cyrix.c
--- ./arch/x86/kernel/cpu/cyrix.c
+++ /tmp/nothing/arch/x86/kernel/cpu/cyrix.c
@@ -224,7 +224,6 @@ static void init_cyrix(struct cpuinfo_x8
*/

switch (dir0_msn) {
- unsigned char tmp;

case 0: /* Cx486SLC/DLC/SRx/DRx */
p = Cx486_name[dir0_lsn & 7];
diff -u -p ./arch/x86/pci/irq.c /tmp/nothing/arch/x86/pci/irq.c
--- ./arch/x86/pci/irq.c
+++ /tmp/nothing/arch/x86/pci/irq.c
@@ -959,7 +959,6 @@ static __init int intel_router_probe(str
return 0;

switch (device) {
- u8 rid;
case PCI_DEVICE_ID_INTEL_82375:
r->name = "PCEB/ESC";
r->get = pirq_esc_get;
diff -u -p ./drivers/acpi/arm64/iort.c /tmp/nothing/drivers/acpi/arm64/iort.c
--- ./drivers/acpi/arm64/iort.c
+++ /tmp/nothing/drivers/acpi/arm64/iort.c
@@ -1667,7 +1667,6 @@ phys_addr_t __init acpi_iort_dma_get_max
break;

switch (node->type) {
- struct acpi_iort_named_component *ncomp;
struct acpi_iort_root_complex *rc;
phys_addr_t local_limit;

diff -u -p ./drivers/infiniband/hw/irdma/hw.c /tmp/nothing/drivers/infiniband/hw/irdma/hw.c
--- ./drivers/infiniband/hw/irdma/hw.c
+++ /tmp/nothing/drivers/infiniband/hw/irdma/hw.c
@@ -267,7 +267,6 @@ static void irdma_process_aeq(struct ird
}

switch (info->ae_id) {
- struct irdma_cm_node *cm_node;
case IRDMA_AE_LLP_CONNECTION_ESTABLISHED:
cm_node = iwqp->cm_node;
if (cm_node->accept_pend) {
diff -u -p ./drivers/infiniband/hw/irdma/utils.c /tmp/nothing/drivers/infiniband/hw/irdma/utils.c
--- ./drivers/infiniband/hw/irdma/utils.c
+++ /tmp/nothing/drivers/infiniband/hw/irdma/utils.c
@@ -1212,7 +1212,6 @@ enum irdma_status_code irdma_hw_modify_q
return status;

switch (m_info->next_iwarp_state) {
- struct irdma_gen_ae_info ae_info;

case IRDMA_QP_STATE_RTS:
case IRDMA_QP_STATE_IDLE:
diff -u -p ./drivers/input/serio/hil_mlc.c /tmp/nothing/drivers/input/serio/hil_mlc.c
--- ./drivers/input/serio/hil_mlc.c
+++ /tmp/nothing/drivers/input/serio/hil_mlc.c
@@ -633,7 +633,6 @@ static int hilse_donode(hil_mlc *mlc)
node = hil_mlc_se + mlc->seidx;

switch (node->act) {
- int rc;
hil_packet pack;

case HILSE_FUNC:
diff -u -p ./drivers/rtc/rtc-pcf8523.c /tmp/nothing/drivers/rtc/rtc-pcf8523.c
--- ./drivers/rtc/rtc-pcf8523.c
+++ /tmp/nothing/drivers/rtc/rtc-pcf8523.c
@@ -242,7 +242,6 @@ static int pcf8523_param_get(struct devi
int ret;

switch(param->param) {
- u32 value;

case RTC_PARAM_BACKUP_SWITCH_MODE:
ret = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL3, &value);
@@ -281,7 +280,6 @@ static int pcf8523_param_set(struct devi
struct pcf8523 *pcf8523 = dev_get_drvdata(dev);

switch(param->param) {
- u8 mode;
case RTC_PARAM_BACKUP_SWITCH_MODE:
switch (param->uvalue) {
case RTC_BSM_DISABLED:
diff -u -p ./drivers/rtc/rtc-rv3028.c /tmp/nothing/drivers/rtc/rtc-rv3028.c
--- ./drivers/rtc/rtc-rv3028.c
+++ /tmp/nothing/drivers/rtc/rtc-rv3028.c
@@ -523,7 +523,6 @@ static int rv3028_param_get(struct devic
int ret;

switch(param->param) {
- u32 value;

case RTC_PARAM_BACKUP_SWITCH_MODE:
ret = regmap_read(rv3028->regmap, RV3028_BACKUP, &value);
@@ -556,7 +555,6 @@ static int rv3028_param_set(struct devic
struct rv3028_data *rv3028 = dev_get_drvdata(dev);

switch(param->param) {
- u8 mode;
case RTC_PARAM_BACKUP_SWITCH_MODE:
switch (param->uvalue) {
case RTC_BSM_DISABLED:
diff -u -p ./drivers/rtc/rtc-rv3032.c /tmp/nothing/drivers/rtc/rtc-rv3032.c
--- ./drivers/rtc/rtc-rv3032.c
+++ /tmp/nothing/drivers/rtc/rtc-rv3032.c
@@ -401,7 +401,6 @@ static int rv3032_param_get(struct devic
int ret;

switch(param->param) {
- u32 value;

case RTC_PARAM_BACKUP_SWITCH_MODE:
ret = regmap_read(rv3032->regmap, RV3032_PMU, &value);
@@ -435,7 +434,6 @@ static int rv3032_param_set(struct devic
struct rv3032_data *rv3032 = dev_get_drvdata(dev);

switch(param->param) {
- u8 mode;
case RTC_PARAM_BACKUP_SWITCH_MODE:
if (rv3032->trickle_charger_set)
return -EINVAL;
diff -u -p ./drivers/s390/net/ctcm_fsms.c /tmp/nothing/drivers/s390/net/ctcm_fsms.c
--- ./drivers/s390/net/ctcm_fsms.c
+++ /tmp/nothing/drivers/s390/net/ctcm_fsms.c
@@ -1432,7 +1432,6 @@ static void ctcmpc_chx_rx(fsm_instance *

again:
switch (fsm_getstate(grp->fsm)) {
- int rc, dolock;
case MPCG_STATE_FLOWC:
case MPCG_STATE_READY:
if (ctcm_checkalloc_buffer(ch))
diff -u -p ./lib/test_stackinit.c /tmp/nothing/lib/test_stackinit.c
--- ./lib/test_stackinit.c
+++ /tmp/nothing/lib/test_stackinit.c
@@ -398,7 +398,6 @@ static int noinline __leaf_switch_none(i
* This is intentionally unreachable. To silence the
* warning, build with -Wno-switch-unreachable
*/
- uint64_t var;

case 1:
target_start = &var;
diff -u -p ./net/mpls/af_mpls.c /tmp/nothing/net/mpls/af_mpls.c
--- ./net/mpls/af_mpls.c
+++ /tmp/nothing/net/mpls/af_mpls.c
@@ -1621,7 +1621,6 @@ static int mpls_dev_notify(struct notifi
return NOTIFY_OK;

switch (event) {
- int err;

case NETDEV_DOWN:
err = mpls_ifdown(dev, event);
diff -u -p ./scripts/recordmcount.c /tmp/nothing/scripts/recordmcount.c
--- ./scripts/recordmcount.c
+++ /tmp/nothing/scripts/recordmcount.c
@@ -488,7 +488,6 @@ static int do_file(char const *const fna
w2 = w2nat;
w8 = w8nat;
switch (ehdr->e_ident[EI_DATA]) {
- static unsigned int const endian = 1;
default:
fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
ehdr->e_ident[EI_DATA], fname);
diff -u -p ./tools/testing/selftests/powerpc/nx-gzip/gunz_test.c /tmp/nothing/tools/testing/selftests/powerpc/nx-gzip/gunz_test.c
--- ./tools/testing/selftests/powerpc/nx-gzip/gunz_test.c
+++ /tmp/nothing/tools/testing/selftests/powerpc/nx-gzip/gunz_test.c
@@ -805,7 +805,6 @@ ok_cc3:
*/

switch (sfbt) {
- int dhtlen;

case 0x0: /* Deflate final EOB received */

diff -u -p ./tools/testing/selftests/proc/read.c /tmp/nothing/tools/testing/selftests/proc/read.c
--- ./tools/testing/selftests/proc/read.c
+++ /tmp/nothing/tools/testing/selftests/proc/read.c
@@ -91,7 +91,6 @@ static void f(DIR *d, unsigned int level
assert(!streq(de->d_name, ".."));

switch (de->d_type) {
- DIR *dd;
int fd;

case DT_REG:
$