watch_queue: Free the page array when watch_queue is dismantled

In the Linux kernel, the following vulnerability has been resolved:

watch_queue: Free the page array when watch_queue is dismantled

Commit 7ea1a0124b6d ("watch_queue: Free the alloc bitmap when the

watch_queue is torn down") took care of the bitmap, but not the page

array.

BUG: memory leak

unreferenced object 0xffff88810d9bc140 (size 32):

comm "syz-executor335", pid 3603, jiffies 4294946994 (age 12.840s)

hex dump (first 32 bytes):

40 a7 40 04 00 ea ff ff 00 00 00 00 00 00 00 00 @.@.............

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

backtrace:

kmalloc_array include/linux/slab.h:621 [inline]

kcalloc include/linux/slab.h:652 [inline]

watch_queue_set_size+0x12f/0x2e0 kernel/watch_queue.c:251

pipe_ioctl+0x82/0x140 fs/pipe.c:632

vfs_ioctl fs/ioctl.c:51 [inline]

__do_sys_ioctl fs/ioctl.c:874 [inline]

__se_sys_ioctl fs/ioctl.c:860 [inline]

__x64_sys_ioctl+0xfc/0x140 fs/ioctl.c:860

do_syscall_x64 arch/x86/entry/common.c:50 [inline]