compat_ptrace_request() lacks handlers for PTRACE_{G,S}ETSIGMASK,
instead using those in ptrace_request(). The compat variant should
read a compat_sigset_t from userspace instead of ptrace_request()s
sigset_t.
While compat_sigset_t is the same size as sigset_t, it is defined as
2xu32, instead of a single u64. On a big-endian CPU this means that
compat_sigset_t is passed to user-space using middle-endianness,
where the least-significant u32 is written most significant byte
first.
If ptrace_request()s code is used userspace will read the most
significant u32 where it expected the least significant.
Instead of duplicating ptrace_request()s code as a special case in
the arch code, handle it here.
CC: Yury Norov <yno...@caviumnetworks.com>
CC: Andrey Vagin <ava...@openvz.org>
Reported-by: Zhou Chengming <zhouchengmi...@huawei.com>
Signed-off-by: James Morse <james.mo...@arm.com>
Fixes: 29000caecbe87 ("ptrace: add ability to get/set signal-blocked mask")
---
LTP test case here:
https://lists.linux.it/pipermail/ltp/2017-June/004932.html
kernel/ptrace.c | 52 ++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 40 insertions(+), 12 deletions(-)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 8d2c10714530..a5bebb6713e8 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -843,6 +843,22 @@ static int ptrace_regset(struct task_struct *task, int
req, unsigned int type,
EXPORT_SYMBOL_GPL(task_user_regset_view);
#endif
+static int ptrace_setsigmask(struct task_struct *child, sigset_t *new_set)
+{
+ sigdelsetmask(new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
+
+ /*
+ * Every thread does recalc_sigpending() after resume, so
+ * retarget_shared_pending() and recalc_sigpending() are not
+ * called here.
+ */
+ spin_lock_irq(&child->sighand->siglock);
+ child->blocked = *new_set;
+ spin_unlock_irq(&child->sighand->siglock);
+
+ return 0;
+}
+
int ptrace_request(struct task_struct *child, long request,
unsigned long addr, unsigned long data)
{
@@ -914,18 +930,7 @@ int ptrace_request(struct task_struct *child, long request,
break;
}
- sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
-
- /*
- * Every thread does recalc_sigpending() after resume, so
- * retarget_shared_pending() and recalc_sigpending() are not
- * called here.
- */
- spin_lock_irq(&child->sighand->siglock);
- child->blocked = new_set;
- spin_unlock_irq(&child->sighand->siglock);
-
- ret = 0;
+ ret = ptrace_setsigmask(child, &new_set);
break;
}
@@ -1149,7 +1154,9 @@ int compat_ptrace_request(struct task_struct *child,
compat_long_t request,
compat_ulong_t addr, compat_ulong_t data)
{
compat_ulong_t __user *datap = compat_ptr(data);
+ compat_sigset_t set32;
compat_ulong_t word;
+ sigset_t new_set;
siginfo_t siginfo;
int ret;
@@ -1189,6 +1196,27 @@ int compat_ptrace_request(struct task_struct *child,
compat_long_t request,
else
ret = ptrace_setsiginfo(child, &siginfo);
break;
+ case PTRACE_GETSIGMASK:
+ if (addr != sizeof(compat_sigset_t))
+ return -EINVAL;
+
+ sigset_to_compat(&set32, &child->blocked);
+
+ if (copy_to_user(datap, &set32, sizeof(set32)))
+ return -EFAULT;
+
+ ret = 0;
+ break;
+ case PTRACE_SETSIGMASK:
+ if (addr != sizeof(compat_sigset_t))
+ return -EINVAL;
+
+ if (copy_from_user(&set32, datap, sizeof(compat_sigset_t)))
+ return -EFAULT;
+
+ sigset_from_compat(&new_set, &set32);
+ ret = ptrace_setsigmask(child, &new_set);
+ break;
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
case PTRACE_GETREGSET:
case PTRACE_SETREGSET:
--
2.11.0
