RE: [PATCH 1/3] treewide: Lift switch variables out of switches

From: Edwin Zimmerman
Date: Thu Jan 24 2019 - 07:58:38 EST

On Wednesday, January 23, 2019 6:04 AM, Kees Cook wrote
>
> Variables declared in a switch statement before any case statements
> cannot be initialized, so move all instances out of the switches.
> After this, future always-initialized stack variables will work
> and not throw warnings like this:
>
> fs/fcntl.c: In function âsend_sigio_to_taskâ:
> fs/fcntl.c:738:13: warning: statement will never be executed [-Wswitch-unreachable]
> siginfo_t si;
> ^~
>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

Reviewed by: Edwin Zimmerman <edwin@xxxxxxxxxxxxxxxxx>

> ---
> arch/x86/xen/enlighten_pv.c | 7 ++++---
> drivers/char/pcmcia/cm4000_cs.c | 2 +-
> drivers/char/ppdev.c | 20 ++++++++-----------
> drivers/gpu/drm/drm_edid.c | 4 ++--
> drivers/gpu/drm/i915/intel_display.c | 2 +-
> drivers/gpu/drm/i915/intel_pm.c | 4 ++--
> drivers/net/ethernet/intel/e1000/e1000_main.c | 3 ++-
> drivers/tty/n_tty.c | 3 +--
> drivers/usb/gadget/udc/net2280.c | 5 ++---
> fs/fcntl.c | 3 ++-
> mm/shmem.c | 5 +++--
> net/core/skbuff.c | 4 ++--
> net/ipv6/ip6_gre.c | 4 ++--
> net/ipv6/ip6_tunnel.c | 4 ++--
> net/openvswitch/flow_netlink.c | 7 +++----
> security/tomoyo/common.c | 3 ++-
> security/tomoyo/condition.c | 7 ++++---
> security/tomoyo/util.c | 4 ++--
> 18 files changed, 45 insertions(+), 46 deletions(-)
>
> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> index c54a493e139a..a79d4b548a08 100644
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -907,14 +907,15 @@ static u64 xen_read_msr_safe(unsigned int msr, int *err)
> static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
> {
> int ret;
> +#ifdef CONFIG_X86_64
> + unsigned which;
> + u64 base;
> +#endif
>
> ret = 0;
>
> switch (msr) {
> #ifdef CONFIG_X86_64
> - unsigned which;
> - u64 base;
> -
> case MSR_FS_BASE: which = SEGBASE_FS; goto set;
> case MSR_KERNEL_GS_BASE: which = SEGBASE_GS_USER; goto set;
> case MSR_GS_BASE: which = SEGBASE_GS_KERNEL; goto set;
> diff --git a/drivers/char/pcmcia/cm4000_cs.c b/drivers/char/pcmcia/cm4000_cs.c
> index 7a4eb86aedac..7211dc0e6f4f 100644
> --- a/drivers/char/pcmcia/cm4000_cs.c
> +++ b/drivers/char/pcmcia/cm4000_cs.c
> @@ -663,6 +663,7 @@ static void monitor_card(struct timer_list *t)
> {
> struct cm4000_dev *dev = from_timer(dev, t, timer);
> unsigned int iobase = dev->p_dev->resource[0]->start;
> + unsigned char flags0;
> unsigned short s;
> struct ptsreq ptsreq;
> int i, atrc;
> @@ -731,7 +732,6 @@ static void monitor_card(struct timer_list *t)
> }
>
> switch (dev->mstate) {
> - unsigned char flags0;
> case M_CARDOFF:
> DEBUGP(4, dev, "M_CARDOFF\n");
> flags0 = inb(REG_FLAGS0(iobase));
> diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c
> index 1ae77b41050a..d77c97e4f996 100644
> --- a/drivers/char/ppdev.c
> +++ b/drivers/char/ppdev.c
> @@ -359,14 +359,19 @@ static int pp_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> struct pp_struct *pp = file->private_data;
> struct parport *port;
> void __user *argp = (void __user *)arg;
> + struct ieee1284_info *info;
> + unsigned char reg;
> + unsigned char mask;
> + int mode;
> + s32 time32[2];
> + s64 time64[2];
> + struct timespec64 ts;
> + int ret;
>
> /* First handle the cases that don't take arguments. */
> switch (cmd) {
> case PPCLAIM:
> {
> - struct ieee1284_info *info;
> - int ret;
> -
> if (pp->flags & PP_CLAIMED) {
> dev_dbg(&pp->pdev->dev, "you've already got it!\n");
> return -EINVAL;
> @@ -517,15 +522,6 @@ static int pp_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>
> port = pp->pdev->port;
> switch (cmd) {
> - struct ieee1284_info *info;
> - unsigned char reg;
> - unsigned char mask;
> - int mode;
> - s32 time32[2];
> - s64 time64[2];
> - struct timespec64 ts;
> - int ret;
> -
> case PPRSTATUS:
> reg = parport_read_status(port);
> if (copy_to_user(argp, &reg, sizeof(reg)))
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index b506e3622b08..8f93956c1628 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -3942,12 +3942,12 @@ static void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid)
> }
>
> for_each_cea_db(cea, i, start, end) {
> + int sad_count;
> +
> db = &cea[i];
> dbl = cea_db_payload_len(db);
>
> switch (cea_db_tag(db)) {
> - int sad_count;
> -
> case AUDIO_BLOCK:
> /* Audio Data Block, contains SADs */
> sad_count = min(dbl / 3, 15 - total_sad_count);
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 3da9c0f9e948..aa1c2ebea456 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -11341,6 +11341,7 @@ static bool check_digital_port_conflicts(struct drm_atomic_state *state)
> drm_for_each_connector_iter(connector, &conn_iter) {
> struct drm_connector_state *connector_state;
> struct intel_encoder *encoder;
> + unsigned int port_mask;
>
> connector_state = drm_atomic_get_new_connector_state(state, connector);
> if (!connector_state)
> @@ -11354,7 +11355,6 @@ static bool check_digital_port_conflicts(struct drm_atomic_state *state)
> WARN_ON(!connector_state->crtc);
>
> switch (encoder->type) {
> - unsigned int port_mask;
> case INTEL_OUTPUT_DDI:
> if (WARN_ON(!HAS_DDI(to_i915(dev))))
> break;
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index a26b4eddda25..c135fdec96b3 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -478,9 +478,9 @@ static void vlv_get_fifo_size(struct intel_crtc_state *crtc_state)
> struct vlv_fifo_state *fifo_state = &crtc_state->wm.vlv.fifo_state;
> enum pipe pipe = crtc->pipe;
> int sprite0_start, sprite1_start;
> + uint32_t dsparb, dsparb2, dsparb3;
>
> switch (pipe) {
> - uint32_t dsparb, dsparb2, dsparb3;
> case PIPE_A:
> dsparb = I915_READ(DSPARB);
> dsparb2 = I915_READ(DSPARB2);
> @@ -1944,6 +1944,7 @@ static void vlv_atomic_update_fifo(struct intel_atomic_state *state,
> const struct vlv_fifo_state *fifo_state =
> &crtc_state->wm.vlv.fifo_state;
> int sprite0_start, sprite1_start, fifo_size;
> + uint32_t dsparb, dsparb2, dsparb3;
>
> if (!crtc_state->fifo_changed)
> return;
> @@ -1969,7 +1970,6 @@ static void vlv_atomic_update_fifo(struct intel_atomic_state *state,
> spin_lock(&dev_priv->uncore.lock);
>
> switch (crtc->pipe) {
> - uint32_t dsparb, dsparb2, dsparb3;
> case PIPE_A:
> dsparb = I915_READ_FW(DSPARB);
> dsparb2 = I915_READ_FW(DSPARB2);
> diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c
> index 8fe9af0e2ab7..041062736845 100644
> --- a/drivers/net/ethernet/intel/e1000/e1000_main.c
> +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
> @@ -3140,8 +3140,9 @@ static netdev_tx_t e1000_xmit_frame(struct sk_buff *skb,
>
> hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
> if (skb->data_len && hdr_len == len) {
> + unsigned int pull_size;
> +
> switch (hw->mac_type) {
> - unsigned int pull_size;
> case e1000_82544:
> /* Make sure we have room to chop off 4 bytes,
> * and that the end alignment will work out to
> diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
> index 5dc9686697cf..eafb39157281 100644
> --- a/drivers/tty/n_tty.c
> +++ b/drivers/tty/n_tty.c
> @@ -634,6 +634,7 @@ static size_t __process_echoes(struct tty_struct *tty)
> while (MASK(ldata->echo_commit) != MASK(tail)) {
> c = echo_buf(ldata, tail);
> if (c == ECHO_OP_START) {
> + unsigned int num_chars, num_bs;
> unsigned char op;
> int no_space_left = 0;
>
> @@ -652,8 +653,6 @@ static size_t __process_echoes(struct tty_struct *tty)
> op = echo_buf(ldata, tail + 1);
>
> switch (op) {
> - unsigned int num_chars, num_bs;
> -
> case ECHO_OP_ERASE_TAB:
> if (MASK(ldata->echo_commit) == MASK(tail + 2))
> goto not_yet_stored;
> diff --git a/drivers/usb/gadget/udc/net2280.c b/drivers/usb/gadget/udc/net2280.c
> index e7dae5379e04..2b275a574e94 100644
> --- a/drivers/usb/gadget/udc/net2280.c
> +++ b/drivers/usb/gadget/udc/net2280.c
> @@ -2854,16 +2854,15 @@ static void ep_clear_seqnum(struct net2280_ep *ep)
> static void handle_stat0_irqs_superspeed(struct net2280 *dev,
> struct net2280_ep *ep, struct usb_ctrlrequest r)
> {
> + struct net2280_ep *e;
> int tmp = 0;
> + u16 status;
>
> #define w_value le16_to_cpu(r.wValue)
> #define w_index le16_to_cpu(r.wIndex)
> #define w_length le16_to_cpu(r.wLength)
>
> switch (r.bRequest) {
> - struct net2280_ep *e;
> - u16 status;
> -
> case USB_REQ_SET_CONFIGURATION:
> dev->addressed_state = !w_value;
> goto usb3_delegate;
> diff --git a/fs/fcntl.c b/fs/fcntl.c
> index 083185174c6d..0640b64ecdc2 100644
> --- a/fs/fcntl.c
> +++ b/fs/fcntl.c
> @@ -725,6 +725,8 @@ static void send_sigio_to_task(struct task_struct *p,
> struct fown_struct *fown,
> int fd, int reason, enum pid_type type)
> {
> + kernel_siginfo_t si;
> +
> /*
> * F_SETSIG can change ->signum lockless in parallel, make
> * sure we read it once and use the same value throughout.
> @@ -735,7 +737,6 @@ static void send_sigio_to_task(struct task_struct *p,
> return;
>
> switch (signum) {
> - kernel_siginfo_t si;
> default:
> /* Queue a rt signal with the appropriate fd as its
> value. We use SI_SIGIO as the source, not
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 6ece1e2fe76e..0b02624dd8b2 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1721,6 +1721,9 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
> swap_free(swap);
>
> } else {
> + loff_t i_size;
> + pgoff_t off;
> +
> if (vma && userfaultfd_missing(vma)) {
> *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
> return 0;
> @@ -1734,8 +1737,6 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
> if (shmem_huge == SHMEM_HUGE_FORCE)
> goto alloc_huge;
> switch (sbinfo->huge) {
> - loff_t i_size;
> - pgoff_t off;
> case SHMEM_HUGE_NEVER:
> goto alloc_nohuge;
> case SHMEM_HUGE_WITHIN_SIZE:
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 26d848484912..7597b3fc9d21 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -4506,9 +4506,9 @@ static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
> typeof(IPPROTO_IP) proto,
> unsigned int off)
> {
> - switch (proto) {
> - int err;
> + int err;
>
> + switch (proto) {
> case IPPROTO_TCP:
> err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
> off + MAX_TCP_HDR_LEN);
> diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
> index b1be67ca6768..9aee1add46c0 100644
> --- a/net/ipv6/ip6_gre.c
> +++ b/net/ipv6/ip6_gre.c
> @@ -427,9 +427,11 @@ static int ip6gre_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
> u8 type, u8 code, int offset, __be32 info)
> {
> struct net *net = dev_net(skb->dev);
> + struct ipv6_tlv_tnl_enc_lim *tel;
> const struct ipv6hdr *ipv6h;
> struct tnl_ptk_info tpi;
> struct ip6_tnl *t;
> + __u32 teli;
>
> if (gre_parse_header(skb, &tpi, NULL, htons(ETH_P_IPV6),
> offset) < 0)
> @@ -442,8 +444,6 @@ static int ip6gre_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
> return -ENOENT;
>
> switch (type) {
> - struct ipv6_tlv_tnl_enc_lim *tel;
> - __u32 teli;
> case ICMPV6_DEST_UNREACH:
> net_dbg_ratelimited("%s: Path to destination invalid or inactive!\n",
> t->parms.name);
> diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
> index 0c6403cf8b52..94ccc7a9037b 100644
> --- a/net/ipv6/ip6_tunnel.c
> +++ b/net/ipv6/ip6_tunnel.c
> @@ -478,10 +478,12 @@ ip6_tnl_err(struct sk_buff *skb, __u8 ipproto, struct inet6_skb_parm *opt,
> struct net *net = dev_net(skb->dev);
> u8 rel_type = ICMPV6_DEST_UNREACH;
> u8 rel_code = ICMPV6_ADDR_UNREACH;
> + struct ipv6_tlv_tnl_enc_lim *tel;
> __u32 rel_info = 0;
> struct ip6_tnl *t;
> int err = -ENOENT;
> int rel_msg = 0;
> + __u32 mtu, teli;
> u8 tproto;
> __u16 len;
>
> @@ -501,8 +503,6 @@ ip6_tnl_err(struct sk_buff *skb, __u8 ipproto, struct inet6_skb_parm *opt,
> err = 0;
>
> switch (*type) {
> - struct ipv6_tlv_tnl_enc_lim *tel;
> - __u32 mtu, teli;
> case ICMPV6_DEST_UNREACH:
> net_dbg_ratelimited("%s: Path to destination invalid or inactive!\n",
> t->parms.name);
> diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
> index 691da853bef5..dee2f9516ae8 100644
> --- a/net/openvswitch/flow_netlink.c
> +++ b/net/openvswitch/flow_netlink.c
> @@ -2652,8 +2652,11 @@ static int validate_set(const struct nlattr *a,
> u8 mac_proto, __be16 eth_type, bool masked, bool log)
> {
> const struct nlattr *ovs_key = nla_data(a);
> + const struct ovs_key_ipv4 *ipv4_key;
> + const struct ovs_key_ipv6 *ipv6_key;
> int key_type = nla_type(ovs_key);
> size_t key_len;
> + int err;
>
> /* There can be only one key in a action */
> if (nla_total_size(nla_len(ovs_key)) != nla_len(a))
> @@ -2671,10 +2674,6 @@ static int validate_set(const struct nlattr *a,
> return -EINVAL;
>
> switch (key_type) {
> - const struct ovs_key_ipv4 *ipv4_key;
> - const struct ovs_key_ipv6 *ipv6_key;
> - int err;
> -
> case OVS_KEY_ATTR_PRIORITY:
> case OVS_KEY_ATTR_SKB_MARK:
> case OVS_KEY_ATTR_CT_MARK:
> diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
> index c598aa00d5e3..bedbd0518153 100644
> --- a/security/tomoyo/common.c
> +++ b/security/tomoyo/common.c
> @@ -1583,8 +1583,9 @@ static void tomoyo_read_domain(struct tomoyo_io_buffer *head)
> list_for_each_cookie(head->r.domain, &tomoyo_domain_list) {
> struct tomoyo_domain_info *domain =
> list_entry(head->r.domain, typeof(*domain), list);
> + u8 i;
> +
> switch (head->r.step) {
> - u8 i;
> case 0:
> if (domain->is_deleted &&
> !head->r.print_this_domain_only)
> diff --git a/security/tomoyo/condition.c b/security/tomoyo/condition.c
> index 8d0e1b9c9c57..c10d903febe5 100644
> --- a/security/tomoyo/condition.c
> +++ b/security/tomoyo/condition.c
> @@ -787,10 +787,11 @@ bool tomoyo_condition(struct tomoyo_request_info *r,
> /* Check string expressions. */
> if (right == TOMOYO_NAME_UNION) {
> const struct tomoyo_name_union *ptr = names_p++;
> + struct tomoyo_path_info *symlink;
> + struct tomoyo_execve *ee;
> + struct file *file;
> +
> switch (left) {
> - struct tomoyo_path_info *symlink;
> - struct tomoyo_execve *ee;
> - struct file *file;
> case TOMOYO_SYMLINK_TARGET:
> symlink = obj ? obj->symlink_target : NULL;
> if (!symlink ||
> diff --git a/security/tomoyo/util.c b/security/tomoyo/util.c
> index badffc8271c8..8e2bb36df37b 100644
> --- a/security/tomoyo/util.c
> +++ b/security/tomoyo/util.c
> @@ -668,6 +668,8 @@ static bool tomoyo_file_matches_pattern2(const char *filename,
> {
> while (filename < filename_end && pattern < pattern_end) {
> char c;
> + int i, j;
> +
> if (*pattern != '\\') {
> if (*filename++ != *pattern++)
> return false;
> @@ -676,8 +678,6 @@ static bool tomoyo_file_matches_pattern2(const char *filename,
> c = *filename;
> pattern++;
> switch (*pattern) {
> - int i;
> - int j;
> case '?':
> if (c == '/') {
> return false;
> --
> 2.17.1