• Christian Brauner's avatar
    fork: return proper negative error code · 28dd29c0
    Christian Brauner authored
    Make sure to return a proper negative error code from copy_process()
    when anon_inode_getfile() fails with CLONE_PIDFD.
    Otherwise _do_fork() will not detect an error and get_task_pid() will
    operator on a nonsensical pointer:
    
    R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c
    R13: 00007ffc15fbb0ff R14: 00007ff07e47e9c0 R15: 0000000000000000
    kasan: CONFIG_KASAN_INLINE enabled
    kasan: GPF could be caused by NULL-ptr deref or user memory access
    general protection fault: 0000 [#1] PREEMPT SMP KASAN
    CPU: 1 PID: 7990 Comm: syz-executor290 Not tainted 5.2.0-rc6+ #9
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
    Google 01/01/2011
    RIP: 0010:__read_once_size include/linux/compiler.h:194 [inline]
    RIP: 0010:get_task_pid+0xe1/0x210 kernel/pid.c:372
    Code: 89 ff e8 62 27 5f 00 49 8b 07 44 89 f1 4c 8d bc c8 90 01 00 00 eb 0c
    e8 0d fe 25 00 49 81 c7 38 05 00 00 4c 89 f8 48 c1 e8 03 <80> 3c 18 00 74
    08 4c 89 ff e8 31 27 5f 00 4d 8b 37 e8 f9 47 12 00
    RSP: 0018:ffff88808a4a7d78 EFLAGS: 00010203
    RAX: 00000000000000a7 RBX: dffffc0000000000 RCX: ffff888088180600
    RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
    RBP: ffff88808a4a7d90 R08: ffffffff814fb3a8 R09: ffffed1015d66bf8
    R10: ffffed1015d66bf8 R11: 1ffff11015d66bf7 R12: 0000000000041ffc
    R13: 1ffff11011494fbc R14: 0000000000000000 R15: 000000000000053d
    FS:  00007ff07e47e700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 00000000004b5100 CR3: 0000000094df2000 CR4: 00000000001406e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
      _do_fork+0x1b9/0x5f0 kernel/fork.c:2360
      __do_sys_clone kernel/fork.c:2454 [inline]
      __se_sys_clone kernel/fork.c:2448 [inline]
      __x64_sys_clone+0xc1/0xd0 kernel/fork.c:2448
      do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301
      entry_SYSCALL_64_after_hwframe+0x49/0xbe
    
    Link: https://lore.kernel.org/lkml/000000000000e0dc0d058c9e7142@google.com
    Reported-and-tested-by: syzbot+002e636502bc4b64eb5c@syzkaller.appspotmail.com
    Fixes: 6fd2fe49 ("copy_process(): don't use ksys_close() on cleanups")
    Cc: Jann Horn <jannh@google.com>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Signed-off-by: default avatarChristian Brauner <christian@brauner.io>
    28dd29c0
fork.c 66.4 KB