From acdedd99b0f3bff9b4bb2103a6b1268c03d1f963 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 30 Apr 2013 15:28:13 -0700 Subject: [PATCH] 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 Tested-by: Mandeep Singh Baines Cc: Ingo Molnar Cc: Neil Horman Cc: "Rafael J. Wysocki" Cc: Roland McGrath Cc: Tejun Heo Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/coredump.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 6fea59043532..acc4448c28e7 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -390,12 +390,14 @@ static int coredump_wait(int exit_code, struct core_state *core_state) 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, @@ -638,9 +641,7 @@ 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); @@ -653,7 +654,7 @@ 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); -- 2.39.2