+++ This bug was initially created as a clone of Bug #312951 +++

The rawhide problem is present also in F6.

Description of problem:
-- Additional comment from adobriyan on 2007-05-29 03:55 EST --
We saw the following oops on rhel5 utrace code

BUG: unable to handle kernel paging request at virtual address 7ca1c291
EIP is at utrace_get_signal+0x46/0x477
          get_signal_to_deliver+0xdf/0x3b1
          do_notify_resume+0xa9/0x6a5
          audit_syscall_exit+0x285/0x2a1
          work_notifysig+0x13/0x19
          copy_to_user_policy+0x73/0x7f

The failing IP corresponds to code in utrace_get_signal():

int
utrace_get_signal(struct task_struct *tsk, struct pt_regs *regs,
                  siginfo_t *info, struct k_sigaction *return_ka)
{
        struct utrace *utrace = tsk->utrace;
                ...
        if (utrace->u.live.signal != NULL) {
                signal.signr = utrace->u.live.signal->signr;
                copy_siginfo(info, utrace->u.live.signal->info);
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^

Bogus pointer was supplied here.

How ->utrace assignment should be handled correctly?
---------------------------------------------------------------------

On (2 CPUs; qemu-kvm) kernel-2.6.22.7-57.fc6.x86_64 seen:

------------[ cut here ]------------
kernel BUG at kernel/utrace.c:328!
invalid opcode: 0000 [1] SMP 
last sysfs file: /class/sound/sequencer2/dev
CPU 0 
Modules linked in: snd_hda_intel snd_usb_audio snd_seq_dummy snd_seq_oss
snd_seq_midi_event snd_seq snd_pcm_oss snd_mixer_oss snd_pcm snd_timer
snd_page_alloc snd_usb_lib snd_rawmidi snd_seq_device snd_hwdep snd soundcore
nfs nfsd exportfs lockd nfs_acl sunrpc ipv6 dm_mirror dm_mod video sbs button
dock battery ac floppy 8139too parport_pc 8139cp ide_cd mii cdrom parport
ata_piix ahci libata sd_mod scsi_mod ext3 jbd mbcache uhci_hcd ohci_hcd ehci_hcd
Pid: 407, comm: clone-get-signa Not tainted 2.6.22.7-57.fc6 #1
RIP: 0010:[<ffffffff81068116>]  [<ffffffff81068116>] check_dead_utrace+0xf2/0x158
RSP: 0018:ffff810008ee3ca8  EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff81000919e800 RCX: 0000000000000000
RDX: 0000000000000008 RSI: ffff810009b90280 RDI: ffff81000919e800
RBP: 0000000000000000 R08: ffff81000d681030 R09: ffff810009b47c98
R10: 0000000000000001 R11: ffff810008ee3f58 R12: ffff810009b90280
R13: 0000000000000000 R14: 0000000000000000 R15: ffff81000919e7d8
FS:  00002aaaaaac2240(0000) GS:ffffffff813ed000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 000000304b550904 CR3: 0000000008f4b000 CR4: 00000000000006e0
Process clone-get-signa (pid: 407, threadinfo ffff810008ee2000, task
ffff81000919e000)
Stack:  ffffffff81067eec ffff81000919e800 0000000000000000 000000000007e569
 000000000007e569 ffffffff8106887d ffff810009b90280 ffff81000919e800
 ffff810009b90c80 ffffffff810689da 0000000000000044 ffff81000d681030
Call Trace:
 [<ffffffff81067eec>] remove_engine+0x76/0x95
 [<ffffffff8106887d>] wake_quiescent+0x4f/0x10d
 [<ffffffff810689da>] utrace_detach+0x9f/0xb2
 [<ffffffff8106b71f>] ptrace_exit+0x63/0xf2
 [<ffffffff8107642e>] zone_statistics+0x3f/0x60
 [<ffffffff81037545>] do_exit+0x144/0x7db
 [<ffffffff81037c5b>] sys_exit_group+0x0/0xe
 [<ffffffff8103eb26>] get_signal_to_deliver+0x3a5/0x3d3
 [<ffffffff81009053>] do_notify_resume+0x9c/0x726
 [<ffffffff8102ab11>] enqueue_task+0x3c/0x4f
 [<ffffffff8102aedd>] update_curr_load+0x6c/0x82
 [<ffffffff8102c09a>] __check_preempt_curr_fair+0x5c/0x7d
 [<ffffffff8126c783>] thread_return+0x0/0xd8
 [<ffffffff81062222>] audit_syscall_exit+0x33d/0x35c
 [<ffffffff81009d6f>] int_signal+0x12/0x17


Code: 0f 0b eb fe 4c 89 e7 e8 e9 fd ff ff 49 83 fd 10 75 35 8b b3 
RIP  [<ffffffff81068116>] check_dead_utrace+0xf2/0x158
 RSP <ffff810008ee3ca8>
Fixing recursive fault but reboot is needed!

---------------------------------------------------------------------


Version-Release number of selected component (if applicable):
kernel-2.6.22.7-57.fc6.x86_64

How reproducible:
After 42 runs of the testcase; testcase has 2000 internal loops =>
=> approx. 84000th cycle.

Steps to Reproduce:
1. gcc -o ./clone-get-signal ./clone-get-signal.c -Wall -ggdb2
2. while ./clone-get-signal ;do echo -n .;done

Actual results:
Kernel crash.

Expected results:
No kernel crash, just infinite dotting.