coredump: elf_core_dump: skip kernel threads (24d5288f) · Commits · 戴 / test

linux_binfmt->core_dump() runs before the process does exit_aio(), this means that we can hit the kernel thread which shares the same ->mm. Afaics, nothing really bad can happen, but perhaps it makes sense to fix this minor bug. It is sad we have to iterate over all threads in system and use GFP_ATOMIC. Hopefully we can kill theses ugly do_each_thread()s, but this needs some nontrivial changes in mm_struct and do_coredump. Signed-off-by:

Oleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/binfmt_elf.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -1520,6 +1520,9 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
		rcu_read_lock();
		do_each_thread(g, p)
		if (p->mm == dump_task->mm) {
		if (p->flags & PF_KTHREAD)
		continue;

		t = kzalloc(offsetof(struct elf_thread_core_info,
		notes[info->thread_notes]),
		GFP_ATOMIC);
		@@ -1724,6 +1727,9 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
		rcu_read_lock();
		do_each_thread(g, p)
		if (current->mm == p->mm && current != p) {
		if (p->flags & PF_KTHREAD)
		continue;

		ets = kzalloc(sizeof(*ets), GFP_ATOMIC);
		if (!ets) {
		rcu_read_unlock();

fs/binfmt_elf_fdpic.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -1626,6 +1626,9 @@ static int elf_fdpic_core_dump(long signr, struct pt_regs *regs,
		rcu_read_lock();
		do_each_thread(g,p)
		if (current->mm == p->mm && current != p) {
		if (p->flags & PF_KTHREAD)
		continue;

		tmp = kzalloc(sizeof(*tmp), GFP_ATOMIC);
		if (!tmp) {
		rcu_read_unlock();

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