| Message ID | 20181205033423.26242-1-ravi.bangoria@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] Uprobes: Fix kernel oops with delayed_uprobe_remove() | expand |
* Ravi Bangoria <ravi.bangoria@linux.ibm.com> [2018-12-05 09:04:23]: > There could be a race between task exit and probe unregister: > > exit_mm() > mmput() > __mmput() uprobe_unregister() > uprobe_clear_state() put_uprobe() > delayed_uprobe_remove() delayed_uprobe_remove() > > put_uprobe() is calling delayed_uprobe_remove() without taking > delayed_uprobe_lock and thus the race sometimes results in a > kernel crash. Fix this by taking delayed_uprobe_lock before > calling delayed_uprobe_remove() from put_uprobe(). > > Detailed crash log can be found at: > https://lkml.org/lkml/2018/11/1/1244 > > Reported-by: syzbot+cb1fb754b771caca0a88@syzkaller.appspotmail.com > Fixes: 1cc33161a83d ("uprobes: Support SDT markers having reference count (semaphore)") > Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Looks good to me. Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> > --- > kernel/events/uprobes.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 322e97bbb437..abbd8da9ac21 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -572,7 +572,9 @@ static void put_uprobe(struct uprobe *uprobe) > * gets called, we don't get a chance to remove uprobe from > * delayed_uprobe_list from remove_breakpoint(). Do it here. > */ > + mutex_lock(&delayed_uprobe_lock); > delayed_uprobe_remove(uprobe, NULL); > + mutex_unlock(&delayed_uprobe_lock); > kfree(uprobe); > } > } > -- > 2.19.2 >
On 12/05, Ravi Bangoria wrote: > > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -572,7 +572,9 @@ static void put_uprobe(struct uprobe *uprobe) > * gets called, we don't get a chance to remove uprobe from > * delayed_uprobe_list from remove_breakpoint(). Do it here. > */ > + mutex_lock(&delayed_uprobe_lock); > delayed_uprobe_remove(uprobe, NULL); > + mutex_unlock(&delayed_uprobe_lock); > kfree(uprobe); Acked-by: Oleg Nesterov <oleg@redhat.com>
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 322e97bbb437..abbd8da9ac21 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -572,7 +572,9 @@ static void put_uprobe(struct uprobe *uprobe) * gets called, we don't get a chance to remove uprobe from * delayed_uprobe_list from remove_breakpoint(). Do it here. */ + mutex_lock(&delayed_uprobe_lock); delayed_uprobe_remove(uprobe, NULL); + mutex_unlock(&delayed_uprobe_lock); kfree(uprobe); } }
There could be a race between task exit and probe unregister: exit_mm() mmput() __mmput() uprobe_unregister() uprobe_clear_state() put_uprobe() delayed_uprobe_remove() delayed_uprobe_remove() put_uprobe() is calling delayed_uprobe_remove() without taking delayed_uprobe_lock and thus the race sometimes results in a kernel crash. Fix this by taking delayed_uprobe_lock before calling delayed_uprobe_remove() from put_uprobe(). Detailed crash log can be found at: https://lkml.org/lkml/2018/11/1/1244 Reported-by: syzbot+cb1fb754b771caca0a88@syzkaller.appspotmail.com Fixes: 1cc33161a83d ("uprobes: Support SDT markers having reference count (semaphore)") Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> --- kernel/events/uprobes.c | 2 ++ 1 file changed, 2 insertions(+)