Messages in this thread Patch in this message | | | Date | Wed, 29 Sep 2021 11:09:12 -0700 | From | Kees Cook <> | Subject | Re: [PATCH 1/5] kernel: replace sizeof(task->comm) with TASK_COMM_LEN |
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On Wed, Sep 29, 2021 at 11:50:32AM +0000, Yafang Shao wrote: > We can use TASK_COMM_LEN directly instread of sizeof(task->comm).
This change makes sense if we accept performing allocation for task->comm, but I don't think that's a good idea. I'll reply to those patches...
> This patch also replace strlcpy with strscpy, to fix the warning by > checkpatch - > WARNING: Prefer strscpy over strlcpy - see: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/
I like this part of the patch, though! :)
-Kees
> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > --- > arch/ia64/kernel/mca.c | 6 +++--- > drivers/block/drbd/drbd_main.c | 2 +- > drivers/hwtracing/stm/core.c | 2 +- > drivers/tty/tty_audit.c | 2 +- > fs/exec.c | 2 +- > kernel/audit.c | 4 ++-- > kernel/auditsc.c | 4 ++-- > kernel/capability.c | 4 ++-- > kernel/futex.c | 2 +- > kernel/sys.c | 2 +- > kernel/trace/blktrace.c | 2 +- > security/lsm_audit.c | 4 ++-- > security/selinux/selinuxfs.c | 2 +- > security/yama/yama_lsm.c | 2 +- > sound/core/oss/pcm_oss.c | 2 +- > 15 files changed, 21 insertions(+), 21 deletions(-) > > diff --git a/arch/ia64/kernel/mca.c b/arch/ia64/kernel/mca.c > index e628a88607bb..4ee86e91ff5e 100644 > --- a/arch/ia64/kernel/mca.c > +++ b/arch/ia64/kernel/mca.c > @@ -875,7 +875,7 @@ copy_reg(const u64 *fr, u64 fnat, unsigned long *tr, unsigned long *tnat) > static void > ia64_mca_modify_comm(const struct task_struct *previous_current) > { > - char *p, comm[sizeof(current->comm)]; > + char *p, comm[TASK_COMM_LEN]; > if (previous_current->pid) > snprintf(comm, sizeof(comm), "%s %d", > current->comm, previous_current->pid); > @@ -889,7 +889,7 @@ ia64_mca_modify_comm(const struct task_struct *previous_current) > current->comm, l, previous_current->comm, > task_thread_info(previous_current)->cpu); > } > - memcpy(current->comm, comm, sizeof(current->comm)); > + memcpy(current->comm, comm, TASK_COMM_LEN); > } > > static void > @@ -1794,7 +1794,7 @@ format_mca_init_stack(void *mca_data, unsigned long offset, > p->parent = p->real_parent = p->group_leader = p; > INIT_LIST_HEAD(&p->children); > INIT_LIST_HEAD(&p->sibling); > - strncpy(p->comm, type, sizeof(p->comm)-1); > + strncpy(p->comm, type, TASK_COMM_LEN-1); > } > > /* Caller prevents this from being called after init */ > diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c > index 55234a558e98..a7cf062e76ab 100644 > --- a/drivers/block/drbd/drbd_main.c > +++ b/drivers/block/drbd/drbd_main.c > @@ -306,7 +306,7 @@ static int drbd_thread_setup(void *arg) > unsigned long flags; > int retval; > > - snprintf(current->comm, sizeof(current->comm), "drbd_%c_%s", > + snprintf(current->comm, TASK_COMM_LEN, "drbd_%c_%s", > thi->name[0], > resource->name); > > diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c > index 2712e699ba08..8ec0a34a9ba6 100644 > --- a/drivers/hwtracing/stm/core.c > +++ b/drivers/hwtracing/stm/core.c > @@ -631,7 +631,7 @@ static ssize_t stm_char_write(struct file *file, const char __user *buf, > * point, try to use the task name and "default" policy entries. > */ > if (!stmf->output.nr_chans) { > - char comm[sizeof(current->comm)]; > + char comm[TASK_COMM_LEN]; > char *ids[] = { comm, "default", NULL }; > > get_task_comm(comm, current); > diff --git a/drivers/tty/tty_audit.c b/drivers/tty/tty_audit.c > index ca7afd7b2716..b98b1aef5f6f 100644 > --- a/drivers/tty/tty_audit.c > +++ b/drivers/tty/tty_audit.c > @@ -69,7 +69,7 @@ static void tty_audit_log(const char *description, dev_t dev, > > ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_TTY); > if (ab) { > - char name[sizeof(current->comm)]; > + char name[TASK_COMM_LEN]; > > audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d" > " minor=%d comm=", description, pid, uid, > diff --git a/fs/exec.c b/fs/exec.c > index a098c133d8d7..021c9dc727bc 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1224,7 +1224,7 @@ void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec) > { > task_lock(tsk); > trace_task_rename(tsk, buf); > - strlcpy(tsk->comm, buf, sizeof(tsk->comm)); > + strscpy(tsk->comm, buf, TASK_COMM_LEN); > task_unlock(tsk); > perf_event_comm(tsk, exec); > } > diff --git a/kernel/audit.c b/kernel/audit.c > index 121d37e700a6..1fbd036e77be 100644 > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -1549,7 +1549,7 @@ static void audit_log_multicast(int group, const char *op, int err) > { > const struct cred *cred; > struct tty_struct *tty; > - char comm[sizeof(current->comm)]; > + char comm[TASK_COMM_LEN]; > struct audit_buffer *ab; > > if (!audit_enabled) > @@ -2192,7 +2192,7 @@ void audit_put_tty(struct tty_struct *tty) > void audit_log_task_info(struct audit_buffer *ab) > { > const struct cred *cred; > - char comm[sizeof(current->comm)]; > + char comm[TASK_COMM_LEN]; > struct tty_struct *tty; > > if (!ab) > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > index 8dd73a64f921..295376d7d926 100644 > --- a/kernel/auditsc.c > +++ b/kernel/auditsc.c > @@ -2595,7 +2595,7 @@ void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries, > enum audit_nfcfgop op, gfp_t gfp) > { > struct audit_buffer *ab; > - char comm[sizeof(current->comm)]; > + char comm[TASK_COMM_LEN]; > > ab = audit_log_start(audit_context(), gfp, AUDIT_NETFILTER_CFG); > if (!ab) > @@ -2616,7 +2616,7 @@ static void audit_log_task(struct audit_buffer *ab) > kuid_t auid, uid; > kgid_t gid; > unsigned int sessionid; > - char comm[sizeof(current->comm)]; > + char comm[TASK_COMM_LEN]; > > auid = audit_get_loginuid(current); > sessionid = audit_get_sessionid(current); > diff --git a/kernel/capability.c b/kernel/capability.c > index 46a361dde042..4033ee837f63 100644 > --- a/kernel/capability.c > +++ b/kernel/capability.c > @@ -45,7 +45,7 @@ __setup("no_file_caps", file_caps_disable); > > static void warn_legacy_capability_use(void) > { > - char name[sizeof(current->comm)]; > + char name[TASK_COMM_LEN]; > > pr_info_once("warning: `%s' uses 32-bit capabilities (legacy support in use)\n", > get_task_comm(name, current)); > @@ -69,7 +69,7 @@ static void warn_legacy_capability_use(void) > > static void warn_deprecated_v2(void) > { > - char name[sizeof(current->comm)]; > + char name[TASK_COMM_LEN]; > > pr_info_once("warning: `%s' uses deprecated v2 capabilities in a way that may be insecure\n", > get_task_comm(name, current)); > diff --git a/kernel/futex.c b/kernel/futex.c > index c15ad276fd15..6cd08156611e 100644 > --- a/kernel/futex.c > +++ b/kernel/futex.c > @@ -1703,7 +1703,7 @@ static int futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr) > > if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) { > if (oparg < 0 || oparg > 31) { > - char comm[sizeof(current->comm)]; > + char comm[TASK_COMM_LEN]; > /* > * kill this print and return -EINVAL when userspace > * is sane again > diff --git a/kernel/sys.c b/kernel/sys.c > index 8fdac0d90504..bea1120c5579 100644 > --- a/kernel/sys.c > +++ b/kernel/sys.c > @@ -2265,7 +2265,7 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, > unsigned long, arg4, unsigned long, arg5) > { > struct task_struct *me = current; > - unsigned char comm[sizeof(me->comm)]; > + unsigned char comm[TASK_COMM_LEN]; > long error; > > error = security_task_prctl(option, arg2, arg3, arg4, arg5); > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c > index c221e4c3f625..009f77ebda5a 100644 > --- a/kernel/trace/blktrace.c > +++ b/kernel/trace/blktrace.c > @@ -124,7 +124,7 @@ static void trace_note_tsk(struct task_struct *tsk) > spin_lock_irqsave(&running_trace_lock, flags); > list_for_each_entry(bt, &running_trace_list, running_list) { > trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, > - sizeof(tsk->comm), 0); > + TASK_COMM_LEN, 0); > } > spin_unlock_irqrestore(&running_trace_lock, flags); > } > diff --git a/security/lsm_audit.c b/security/lsm_audit.c > index 5a5016ef43b0..eec54cb48845 100644 > --- a/security/lsm_audit.c > +++ b/security/lsm_audit.c > @@ -208,7 +208,7 @@ static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr, > static void dump_common_audit_data(struct audit_buffer *ab, > struct common_audit_data *a) > { > - char comm[sizeof(current->comm)]; > + char comm[TASK_COMM_LEN]; > > /* > * To keep stack sizes in check force programers to notice if they > @@ -310,7 +310,7 @@ static void dump_common_audit_data(struct audit_buffer *ab, > if (tsk) { > pid_t pid = task_tgid_nr(tsk); > if (pid) { > - char comm[sizeof(tsk->comm)]; > + char comm[TASK_COMM_LEN]; > audit_log_format(ab, " opid=%d ocomm=", pid); > audit_log_untrustedstring(ab, > memcpy(comm, tsk->comm, sizeof(comm))); > diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c > index e4cd7cb856f3..e529db76502d 100644 > --- a/security/selinux/selinuxfs.c > +++ b/security/selinux/selinuxfs.c > @@ -752,7 +752,7 @@ static ssize_t sel_write_checkreqprot(struct file *file, const char __user *buf, > goto out; > > if (new_value) { > - char comm[sizeof(current->comm)]; > + char comm[TASK_COMM_LEN]; > > memcpy(comm, current->comm, sizeof(comm)); > pr_warn_once("SELinux: %s (%d) set checkreqprot to 1. This is deprecated and will be rejected in a future kernel release.\n", > diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c > index 06e226166aab..178d7a138e98 100644 > --- a/security/yama/yama_lsm.c > +++ b/security/yama/yama_lsm.c > @@ -75,7 +75,7 @@ static void report_access(const char *access, struct task_struct *target, > struct task_struct *agent) > { > struct access_report_info *info; > - char agent_comm[sizeof(agent->comm)]; > + char agent_comm[TASK_COMM_LEN]; > > assert_spin_locked(&target->alloc_lock); /* for target->comm */ > > diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c > index 82a818734a5f..d541530236e1 100644 > --- a/sound/core/oss/pcm_oss.c > +++ b/sound/core/oss/pcm_oss.c > @@ -2460,7 +2460,7 @@ static int snd_task_name(struct task_struct *task, char *name, size_t size) > > if (snd_BUG_ON(!task || !name || size < 2)) > return -EINVAL; > - for (idx = 0; idx < sizeof(task->comm) && idx + 1 < size; idx++) > + for (idx = 0; idx < TASK_COMM_LEN && idx + 1 < size; idx++) > name[idx] = task->comm[idx]; > name[idx] = '\0'; > return 0; > -- > 2.17.1 >
-- Kees Cook
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