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Commit 3b34fc58 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

elf_core_dump: use rcu_read_lock() to access ->real_parent 



In theory it is not safe to dereference ->parent/real_parent without
tasklist or rcu lock, we can race with re-parenting.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarRoland McGrath <roland@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 72a1de39

fs/binfmt_elf.c

+6 −2
Original line number Diff line number Diff line
@@ -1340,8 +1340,10 @@ static void fill_prstatus(struct elf_prstatus *prstatus, 
	prstatus->pr_info.si_signo = prstatus->pr_cursig = signr;

	prstatus->pr_sigpend = p->pending.signal.sig[0];

	prstatus->pr_sighold = p->blocked.sig[0];

	rcu_read_lock();

	prstatus->pr_ppid = task_pid_vnr(rcu_dereference(p->real_parent));

	rcu_read_unlock();

	prstatus->pr_pid = task_pid_vnr(p);

	prstatus->pr_ppid = task_pid_vnr(p->real_parent);

	prstatus->pr_pgrp = task_pgrp_vnr(p);

	prstatus->pr_sid = task_session_vnr(p);

	if (thread_group_leader(p)) {
@@ -1382,8 +1384,10 @@ static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p, 
			psinfo->pr_psargs[i] = ' ';

	psinfo->pr_psargs[len] = 0;



	rcu_read_lock();

	psinfo->pr_ppid = task_pid_vnr(rcu_dereference(p->real_parent));

	rcu_read_unlock();

	psinfo->pr_pid = task_pid_vnr(p);

	psinfo->pr_ppid = task_pid_vnr(p->real_parent);

	psinfo->pr_pgrp = task_pgrp_vnr(p);

	psinfo->pr_sid = task_session_vnr(p);

fs/binfmt_elf_fdpic.c

+6 −2
Original line number Diff line number Diff line
@@ -1387,8 +1387,10 @@ static void fill_prstatus(struct elf_prstatus *prstatus, 
	prstatus->pr_info.si_signo = prstatus->pr_cursig = signr;

	prstatus->pr_sigpend = p->pending.signal.sig[0];

	prstatus->pr_sighold = p->blocked.sig[0];

	rcu_read_lock();

	prstatus->pr_ppid = task_pid_vnr(rcu_dereference(p->real_parent));

	rcu_read_unlock();

	prstatus->pr_pid = task_pid_vnr(p);

	prstatus->pr_ppid = task_pid_vnr(p->real_parent);

	prstatus->pr_pgrp = task_pgrp_vnr(p);

	prstatus->pr_sid = task_session_vnr(p);

	if (thread_group_leader(p)) {
@@ -1432,8 +1434,10 @@ static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p, 
			psinfo->pr_psargs[i] = ' ';

	psinfo->pr_psargs[len] = 0;



	rcu_read_lock();

	psinfo->pr_ppid = task_pid_vnr(rcu_dereference(p->real_parent));

	rcu_read_unlock();

	psinfo->pr_pid = task_pid_vnr(p);

	psinfo->pr_ppid = task_pid_vnr(p->real_parent);

	psinfo->pr_pgrp = task_pgrp_vnr(p);

	psinfo->pr_sid = task_session_vnr(p);