The patch titled
Subject: coredump: sanitize the setting of signal->group_exit_code
has been added to the -mm tree. Its filename is
coredump-sanitize-the-setting-of-signal-group_exit_code.patch
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From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: coredump: sanitize the setting of signal->group_exit_code
Now that the coredumping process can be SIGKILL'ed, the setting of
->group_exit_code in do_coredump() can race with complete_signal() and
SIGKILL or 0x80 can be "lost", or wait(status) can report status ==
SIGKILL | 0x80.
But the main problem is that it is not clear to me what should we do if
binfmt->core_dump() succeeds but SIGKILL was sent, that is why this patch
comes as a separate change.
This patch adds 0x80 if ->core_dump() succeeds and the process was not
killed. But perhaps we can (should?) re-set ->group_exit_code changed by
SIGKILL back to "siginfo->si_signo |= 0x80" in case when core_dumped == T.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Tested-by: Mandeep Singh Baines <msb@xxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Neil Horman <nhorman@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/coredump.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff -puN fs/coredump.c~coredump-sanitize-the-setting-of-signal-group_exit_code fs/coredump.c
--- a/fs/coredump.c~coredump-sanitize-the-setting-of-signal-group_exit_code
+++ a/fs/coredump.c
@@ -390,12 +390,14 @@ static int coredump_wait(int exit_code,
return core_waiters;
}
-static void coredump_finish(struct mm_struct *mm)
+static void coredump_finish(struct mm_struct *mm, bool core_dumped)
{
struct core_thread *curr, *next;
struct task_struct *task;
spin_lock_irq(¤t->sighand->siglock);
+ if (core_dumped && !__fatal_signal_pending(current))
+ current->signal->group_exit_code |= 0x80;
current->signal->group_exit_task = NULL;
current->signal->flags = SIGNAL_GROUP_EXIT;
spin_unlock_irq(¤t->sighand->siglock);
@@ -480,6 +482,7 @@ void do_coredump(siginfo_t *siginfo)
int ispipe;
struct files_struct *displaced;
bool need_nonrelative = false;
+ bool core_dumped = false;
static atomic_t core_dump_count = ATOMIC_INIT(0);
struct coredump_params cprm = {
.siginfo = siginfo,
@@ -632,9 +635,8 @@ void do_coredump(siginfo_t *siginfo)
goto close_fail;
if (displaced)
put_files_struct(displaced);
- retval = binfmt->core_dump(&cprm);
- if (retval)
- current->signal->group_exit_code |= 0x80;
+
+ core_dumped = binfmt->core_dump(&cprm);
if (ispipe && core_pipe_limit)
wait_for_dump_helpers(cprm.file);
@@ -647,7 +649,7 @@ fail_dropcount:
fail_unlock:
kfree(cn.corename);
fail_corename:
- coredump_finish(mm);
+ coredump_finish(mm, core_dumped);
revert_creds(old_cred);
fail_creds:
put_cred(cred);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
linux-next.patch
signal-allow-to-send-any-siginfo-to-itself.patch
kernel-signalc-fix-suboptimal-printk-usage.patch
coredump-only-sigkill-should-interrupt-the-coredumping-task.patch
coredump-ensure-that-sigkill-always-kills-the-dumping-thread.patch
coredump-sanitize-the-setting-of-signal-group_exit_code.patch
vfork-dont-freezer_count-for-in-kernel-users-of-clone_vfork.patch
lockdep-check-that-no-locks-held-at-freeze-time.patch
lockdep-check-that-no-locks-held-at-freeze-time-fix.patch
coredump-cleanup-the-waiting-for-coredump_finish-code.patch
coredump-use-a-freezable_schedule-for-the-coredump_finish-wait.patch
coredump-abort-core-dump-piping-only-due-to-a-fatal-signal.patch
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