Oleg Nesterov
bf959931dd
wait/ptrace: assume __WALL if the child is traced ...
The following program (simplified version of generated by syzkaller)
#include <pthread.h>
#include <unistd.h>
#include <sys/ptrace.h>
#include <stdio.h>
#include <signal.h>
void *thread_func(void *arg)
{
ptrace(PTRACE_TRACEME, 0,0,0);
return 0;
}
int main(void)
{
pthread_t thread;
if (fork())
return 0;
while (getppid() != 1)
;
pthread_create(&thread, NULL, thread_func, NULL);
pthread_join(thread, NULL);
return 0;
}
creates an unreapable zombie if /sbin/init doesn't use __WALL.
This is not a kernel bug, at least in a sense that everything works as
expected: debugger should reap a traced sub-thread before it can reap the
leader, but without __WALL/__WCLONE do_wait() ignores sub-threads.
Unfortunately, it seems that /sbin/init in most (all?) distributions
doesn't use it and we have to change the kernel to avoid the problem.
Note also that most init's use sys_waitid() which doesn't allow __WALL, so
the necessary user-space fix is not that trivial.
This patch just adds the "ptrace" check into eligible_child(). To some
degree this matches the "tsk->ptrace" in exit_notify(), ->exit_signal is
mostly ignored when the tracee reports to debugger. Or WSTOPPED, the
tracer doesn't need to set this flag to wait for the stopped tracee.
This obviously means the user-visible change: __WCLONE and __WALL no
longer have any meaning for debugger. And I can only hope that this won't
break something, but at least strace/gdb won't suffer.
We could make a more conservative change. Say, we can take __WCLONE into
account, or !thread_group_leader(). But it would be nice to not
complicate these historical/confusing checks.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: <syzkaller@googlegroups.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-23 17:04:14 -07:00
bpf: teach verifier to recognize imm += ptr pattern
2016-05-20 19:53:03 -04:00
mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings
2016-02-22 08:51:37 +01:00
x86: remove more uaccess_32.h complexity
2016-05-22 17:21:27 -07:00
radix-tree: introduce radix_tree_empty
2016-05-20 17:58:30 -07:00
Merge branches 'for-4.7/core', 'for-4.7/livepatching-doc' and 'for-4.7/livepatching-ppc64' into for-linus
2016-05-17 12:06:35 +02:00
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2016-05-16 14:47:16 -07:00
PM / Hibernate: Call flush_icache_range() on pages restored in-place
2016-04-28 13:35:48 +01:00
printk/nmi: flush NMI messages on the system panic
2016-05-20 17:58:30 -07:00
debugobjects: insulate non-fixup logic related to static obj from fixup callbacks
2016-05-19 19:12:14 -07:00
Power management material for v4.7-rc1
2016-05-16 19:17:22 -07:00
debugobjects: insulate non-fixup logic related to static obj from fixup callbacks
2016-05-19 19:12:14 -07:00
Three more changes.
2016-05-22 19:40:39 -07:00
Merge branch 'stable-4.7' of git://git.infradead.org/users/pcmoore/audit
2016-05-18 18:46:55 -07:00
wrappers for ->i_mutex access
2016-01-22 18:04:28 -05:00
audit: cleanup prune_tree_thread
2016-04-04 09:46:47 -04:00
don't bother with ->d_inode->i_sb - it's always equal to ->d_sb
2016-04-10 17:11:51 -04:00
audit: Fix typo in comment
2016-02-08 11:25:39 -05:00
Merge branch 'stable-4.7' of git://git.infradead.org/users/pcmoore/audit
2016-05-18 18:46:55 -07:00
cgroup: fix compile warning
2016-05-12 11:05:27 -04:00
sched/hotplug: Make activate() the last hotplug step
2016-05-06 14:58:25 +02:00
cpuset: use static key better and convert to new API
2016-05-19 19:12:14 -07:00
kmemcg: account certain kmem allocations to memcg
2016-01-14 16:00:49 -08:00
kmemcg: account certain kmem allocations to memcg
2016-01-14 16:00:49 -08:00
wait/ptrace: assume __WALL if the child is traced
2016-05-23 17:04:14 -07:00
fork: free thread in copy_process on failure
2016-05-20 17:58:30 -07:00
x86: remove more uaccess_32.h complexity
2016-05-22 17:21:27 -07:00
ptrace: use fsuid, fsgid, effective creds for fs access checks
2016-01-20 17:09:18 -08:00
kernel/hung_task.c: use timeout diff when timeout is updated
2016-03-22 15:36:02 -07:00
kallsyms: add support for relative offsets in kallsyms address table
2016-03-15 16:55:16 -07:00
ptrace: use fsuid, fsgid, effective creds for fs access checks
2016-01-20 17:09:18 -08:00
kcov: don't profile branches in kcov
2016-04-28 19:34:04 -07:00
kexec: set KEXEC_TYPE_CRASH before sanity_check_segment_list()
2016-01-20 17:09:18 -08:00
printk/nmi: flush NMI messages on the system panic
2016-05-20 17:58:30 -07:00
Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
2016-03-17 11:33:45 -07:00
kexec: move some memembers and definitions within the scope of CONFIG_KEXEC_FILE
2016-01-20 17:09:18 -08:00
sched/debug: Make schedstats a runtime tunable that is disabled by default
2016-02-09 11:54:23 +01:00
ELF/MIPS build fix
2016-05-23 17:04:14 -07:00
memremap: add arch specific hook for MEMREMAP_WB mappings
2016-04-04 10:26:41 +02:00
module: preserve Elf information for livepatch modules
2016-04-01 15:00:10 +02:00
KEYS: Move the point of trust determination to __key_link()
2016-04-11 22:43:43 +01:00
cgroup: introduce cgroup namespaces
2016-02-16 13:04:58 -05:00
kernel/padata.c: hide unused functions
2016-05-19 19:12:14 -07:00
printk/nmi: flush NMI messages on the system panic
2016-05-20 17:58:30 -07:00
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2016-01-31 15:44:04 -08:00
profile: hide unused functions when !CONFIG_PROC_FS
2016-03-22 15:36:02 -07:00
ptrace: change __ptrace_unlink() to clear ->ptrace under ->siglock
2016-03-22 15:36:02 -07:00
wrappers for ->i_mutex access
2016-01-22 18:04:28 -05:00
/proc/iomem: only expose physical resource addresses to privileged users
2016-04-14 12:56:09 -07:00
Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus
2016-05-19 10:02:26 -07:00
signals/sigaltstack: Report current flag bits in sigaltstack()
2016-05-04 08:34:14 +02:00
Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2016-03-15 13:50:29 -07:00
cpu/hotplug: Unpark smpboot threads from the state machine
2016-03-01 20:36:56 +01:00
cpu/hotplug: Create hotplug threads
2016-03-01 20:36:56 +01:00
arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections
2016-03-25 16:37:42 -07:00
kernel/stop_machine.c: remove CONFIG_SMP dependencies
2016-01-16 11:17:24 -08:00
timer: convert timer_slack_ns from unsigned long to u64
2016-03-17 15:09:34 -07:00
mm: /proc/sys/vm/stat_refresh to force vmstat update
2016-05-19 19:12:14 -07:00
kernel/sysctl_binary.c: use generic UUID library
2016-05-20 17:58:30 -07:00
taskstats: use the libnl API to align nlattr on 64-bit
2016-04-23 20:13:25 -04:00
rcutorture: Dump trace buffer upon shutdown
2016-04-21 13:47:04 -07:00
kernel/...: convert pr_warning to pr_warn
2016-03-22 15:36:02 -07:00
time, acct: Drop irq save & restore from __acct_update_integrals()
2016-02-29 09:53:09 +01:00
watchdog: don't run proc_watchdog_update if new value is same as old
2016-03-17 15:09:34 -07:00
debugobjects: insulate non-fixup logic related to static obj from fixup callbacks
2016-05-19 19:12:14 -07:00
sched/core: Get rid of 'cpu' argument in wq_worker_sleeping()
2016-03-02 10:28:47 -05:00
bf959931dd