From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Howells <dhowells@redhat.com>,
Roland McGrath <roland@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH] elf_core_dump: use rcu_read_lock() to access ->real_parent
Date: Wed, 29 Apr 2009 11:07:46 +0200 [thread overview]
Message-ID: <20090429090746.GA8284@redhat.com> (raw)
(on top of ptrace-s-parent-real_parent-in-binfmt_elf_fdpicc.patch)
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: Oleg Nesterov <oleg@redhat.com>
fs/binfmt_elf.c | 8 ++++++--
fs/binfmt_elf_fdpic.c | 8 ++++++--
2 files changed, 12 insertions(+), 4 deletions(-)
--- PTRACE/fs/binfmt_elf.c~RCU_PARENT 2009-04-06 00:03:40.000000000 +0200
+++ PTRACE/fs/binfmt_elf.c 2009-04-29 10:46:54.000000000 +0200
@@ -1340,8 +1340,10 @@ static void fill_prstatus(struct elf_prs
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_prpsin
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);
--- PTRACE/fs/binfmt_elf_fdpic.c~RCU_PARENT 2009-04-28 21:40:49.000000000 +0200
+++ PTRACE/fs/binfmt_elf_fdpic.c 2009-04-29 10:52:31.000000000 +0200
@@ -1387,8 +1387,10 @@ static void fill_prstatus(struct elf_prs
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_prpsin
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);
next reply other threads:[~2009-04-29 9:13 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-29 9:07 Oleg Nesterov [this message]
2009-04-29 19:46 ` [PATCH] elf_core_dump: use rcu_read_lock() to access ->real_parent Roland McGrath
-- strict thread matches above, loose matches on Subject: below --
2009-04-29 9:06 Oleg Nesterov
2009-04-29 9:46 ` David Howells
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20090429090746.GA8284@redhat.com \
--to=oleg@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=dhowells@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=roland@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox