Call clear_siginfo to ensure stack allocated siginfos are fully
initialized before being passed to the signal sending functions.
This ensures that if there is the kind of confusion documented by
TRAP_FIXME, FPE_FIXME, or BUS_FIXME the kernel won't send unitialized
data to userspace when the kernel generates a signal with SI_USER but
the copy to userspace assumes it is a different kind of signal, and
different fields are initialized.
This also prepares the way for turning copy_siginfo_to_user
into a copy_to_user, by removing the need in many cases to perform
a field by field copy simply to skip the uninitialized fields.
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
fs/fcntl.c | 1 +
ipc/mqueue.c | 1 +
kernel/signal.c | 9 ++++++++-
3 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/fs/fcntl.c b/fs/fcntl.c
index 0522e283a4f4..c17369659f4a 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -737,6 +737,7 @@ static void send_sigio_to_task(struct task_struct *p,
delivered even if we can't queue. Failure to
queue in this case _should_ be reported; we fall
back to SIGIO in that case. --sct */
+ clear_siginfo(&si);
si.si_signo = signum;
si.si_errno = 0;
si.si_code = reason;
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 9649ecd8a73a..17bc8b874d92 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -639,6 +639,7 @@ static void __do_notify(struct mqueue_inode_info *info)
case SIGEV_SIGNAL:
/* sends signal */
+ clear_siginfo(&sig_i);
sig_i.si_signo = info->notify.sigev_signo;
sig_i.si_errno = 0;
sig_i.si_code = SI_MESGQ;
diff --git a/kernel/signal.c b/kernel/signal.c
index fd182a845490..241d54958bbb 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -549,6 +549,7 @@ static void collect_signal(int sig, struct sigpending *list, siginfo_t *info,
* a fast-pathed signal or we must have been
* out of queue space. So zero out the info.
*/
+ clear_siginfo(info);
info->si_signo = sig;
info->si_errno = 0;
info->si_code = SI_USER;
@@ -1043,6 +1044,7 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
list_add_tail(&q->list, &pending->list);
switch ((unsigned long) info) {
case (unsigned long) SEND_SIG_NOINFO:
+ clear_siginfo(&q->info);
q->info.si_signo = sig;
q->info.si_errno = 0;
q->info.si_code = SI_USER;
@@ -1051,6 +1053,7 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
break;
case (unsigned long) SEND_SIG_PRIV:
+ clear_siginfo(&q->info);
q->info.si_signo = sig;
q->info.si_errno = 0;
q->info.si_code = SI_KERNEL;
@@ -1623,6 +1626,7 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
sig = SIGCHLD;
}
+ clear_siginfo(&info);
info.si_signo = sig;
info.si_errno = 0;
/*
@@ -1717,6 +1721,7 @@ static void do_notify_parent_cldstop(struct task_struct *tsk,
parent = tsk->real_parent;
}
+ clear_siginfo(&info);
info.si_signo = SIGCHLD;
info.si_errno = 0;
/*
@@ -1929,7 +1934,7 @@ static void ptrace_do_notify(int signr, int exit_code, int why)
{
siginfo_t info;
- memset(&info, 0, sizeof info);
+ clear_siginfo(&info);
info.si_signo = signr;
info.si_code = exit_code;
info.si_pid = task_pid_vnr(current);
@@ -2136,6 +2141,7 @@ static int ptrace_signal(int signr, siginfo_t *info)
* have updated *info via PTRACE_SETSIGINFO.
*/
if (signr != info->si_signo) {
+ clear_siginfo(info);
info->si_signo = signr;
info->si_errno = 0;
info->si_code = SI_USER;
@@ -2941,6 +2947,7 @@ SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
{
struct siginfo info;
+ clear_siginfo(&info);
info.si_signo = sig;
info.si_errno = 0;
info.si_code = SI_USER;
--
2.14.1
