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Commit 269b005a authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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coredump: shift down_write(mmap_sem) into coredump_wait() 



- move the cprm.mm_flags checks up, before we take mmap_sem

- move down_write(mmap_sem) and ->core_state check from do_coredump()
  to coredump_wait()

This simplifies the code and makes the locking symmetrical.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5e43aef5

fs/exec.c

+7 −12
Original line number Diff line number Diff line
@@ -1662,11 +1662,14 @@ static int coredump_wait(int exit_code, struct core_state *core_state) 
	struct task_struct *tsk = current;

	struct mm_struct *mm = tsk->mm;

	struct completion *vfork_done;

	int core_waiters;

	int core_waiters = -EBUSY;



	init_completion(&core_state->startup);

	core_state->dumper.task = tsk;

	core_state->dumper.next = NULL;



	down_write(&mm->mmap_sem);

	if (!mm->core_state)

		core_waiters = zap_threads(tsk, mm, core_state, exit_code);

	up_write(&mm->mmap_sem);
@@ -1860,20 +1863,12 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs) 
	binfmt = mm->binfmt;

	if (!binfmt || !binfmt->core_dump)

		goto fail;

	if (!__get_dumpable(cprm.mm_flags))

		goto fail;



	cred = prepare_creds();

	if (!cred)

		goto fail;



	down_write(&mm->mmap_sem);

	/*

	 * If another thread got here first, or we are not dumpable, bail out.

	 */

	if (mm->core_state || !__get_dumpable(cprm.mm_flags)) {

		up_write(&mm->mmap_sem);

		goto fail_creds;

	}



	/*

	 *	We cannot trust fsuid as being the "true" uid of the

	 *	process nor do we know its entire history. We only know it