arm64: compat Fix siginfo_t -> compat_siginfo_t conversion on big endian

The native (64-bit) sigval_t union contains sival_int (32-bit) and
sival_ptr (64-bit). When a compat application invokes a syscall that
takes a sigval_t value (as part of a larger structure, e.g.
compat_sys_mq_notify, compat_sys_timer_create), the compat_sigval_t
union is converted to the native sigval_t with sival_int overlapping
with either the least or the most significant half of sival_ptr,
depending on endianness. When the corresponding signal is delivered to a
compat application, on big endian the current (compat_uptr_t)sival_ptr
cast always returns 0 since sival_int corresponds to the top part of
sival_ptr. This patch fixes copy_siginfo_to_user32() so that sival_int
is copied to the compat_siginfo_t structure.

Cc: <stable@vger.kernel.org>
Reported-by: Bamvor Jian Zhang <bamvor.zhangjian@huawei.com>
Tested-by: Bamvor Jian Zhang <bamvor.zhangjian@huawei.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 2 insertions, 3 deletions

diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index c20a300e2213..d26fcd4cd6e6 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -154,8 +154,7 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)
         case __SI_TIMER:
                  err |= __put_user(from->si_tid, &to->si_tid);
                  err |= __put_user(from->si_overrun, &to->si_overrun);
-                 err |= __put_user((compat_uptr_t)(unsigned long)from->si_ptr,
-                                   &to->si_ptr);
+                 err |= __put_user(from->si_int, &to->si_int);
                 break;
         case __SI_POLL:
                 err |= __put_user(from->si_band, &to->si_band);
@@ -184,7 +183,7 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)
         case __SI_MESGQ: /* But this is */
                 err |= __put_user(from->si_pid, &to->si_pid);
                 err |= __put_user(from->si_uid, &to->si_uid);
-                err |= __put_user((compat_uptr_t)(unsigned long)from->si_ptr, &to->si_ptr);
+                err |= __put_user(from->si_int, &to->si_int);
                 break;
         case __SI_SYS:
                 err |= __put_user((compat_uptr_t)(unsigned long)