gigaset: memory leak in gigaset_initcshw

[Dmitry Vyukov]

Hello,

The following program causes a memory leak of ser_cardstate object
allocated in gigaset_initcshw:

// autogenerated by syzkaller (http://github.com/google/syzkaller)
#include <pthread.h>
#include <stdint.h>
#include <string.h>
#include <sys/syscall.h>
#include <unistd.h>

int main()
{
  long r[7];
  memset(r, -1, sizeof(r));
  r[0] = syscall(SYS_mmap, 0x20000000ul, 0x10000ul, 0x3ul, 0x32ul,
                 0xfffffffffffffffful, 0x0ul);
  r[2] = syscall(SYS_open, "/dev/ptmx", 0x8002ul, 0x0ul, 0, 0, 0);
  *(uint32_t*)0x20002b1e = (uint32_t)0x10;
  r[4] = syscall(SYS_ioctl, r[2], 0x5423ul, 0x20002b1eul, 0, 0, 0);
  *(uint32_t*)0x20009000 = (uint32_t)0x7;
  r[6] = syscall(SYS_ioctl, r[2], 0x5423ul, 0x20009000ul, 0, 0, 0);
  return 0;
}

unreferenced object 0xffff88002b4109d8 (size 2048):
  comm "a.out", pid 9565, jiffies 4301785161 (age 10.646s)
  hex dump (first 32 bytes):
    e0 30 0a 87 ff ff ff ff 00 00 00 00 00 00 00 00  .0..............
    80 af 0d 88 ff ff ff ff 88 08 5e 00 00 88 ff ff  ..........^.....
  backtrace:
    [<     inline     >] kzalloc include/linux/slab.h:607
    [<ffffffff84bfbeab>] gigaset_initcshw+0x4b/0x2b0
drivers/isdn/gigaset/ser-gigaset.c:394
    [<ffffffff84bb1e22>] gigaset_initcs+0xf82/0x1660
drivers/isdn/gigaset/common.c:748
    [<ffffffff84bfb65b>] gigaset_tty_open+0x9b/0x460
drivers/isdn/gigaset/ser-gigaset.c:516
    [<ffffffff82f9a648>] tty_ldisc_open.isra.2+0x78/0xd0
drivers/tty/tty_ldisc.c:454
    [<ffffffff82f9ac32>] tty_set_ldisc+0x292/0x8a0 drivers/tty/tty_ldisc.c:561
    [<     inline     >] tiocsetd drivers/tty/tty_io.c:2656
    [<ffffffff82f8390e>] tty_ioctl+0xb2e/0x2160 drivers/tty/tty_io.c:2911
    [<     inline     >] vfs_ioctl fs/ioctl.c:43
    [<ffffffff817fa9ec>] do_vfs_ioctl+0x18c/0xfb0 fs/ioctl.c:674
    [<     inline     >] SYSC_ioctl fs/ioctl.c:689
    [<ffffffff817fb89f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:680
    [<ffffffff8665ebb6>] entry_SYSCALL_64_fastpath+0x16/0x7a
arch/x86/entry/entry_64.S:185

On commit 34229b277480f46c1e9a19f027f30b074512e68b.