From: tip-bot for Andy Lutomirski <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: hpa@zytor.com, bp@alien8.de, brgerst@gmail.com,
peterz@infradead.org, jann@thejh.net, dvlasenk@redhat.com,
torvalds@linux-foundation.org, jpoimboe@redhat.com,
luto@kernel.org, mingo@kernel.org, tglx@linutronix.de,
linux-kernel@vger.kernel.org
Subject: [tip:x86/asm] lib/syscall: Pin the task stack in collect_syscall()
Date: Fri, 16 Sep 2016 02:18:38 -0700 [thread overview]
Message-ID: <tip-aa1f1a639621672b68f654dc815a7d8298ff396f@git.kernel.org> (raw)
In-Reply-To: <0bfd8e6d4729c97745d3781a29610a33d0a8091d.1474003868.git.luto@kernel.org>
Commit-ID: aa1f1a639621672b68f654dc815a7d8298ff396f
Gitweb: http://git.kernel.org/tip/aa1f1a639621672b68f654dc815a7d8298ff396f
Author: Andy Lutomirski <luto@kernel.org>
AuthorDate: Thu, 15 Sep 2016 22:45:47 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 16 Sep 2016 09:18:53 +0200
lib/syscall: Pin the task stack in collect_syscall()
This will avoid a potential read-after-free if collect_syscall()
(e.g. /proc/PID/syscall) is called on an exiting task.
Reported-by: Jann Horn <jann@thejh.net>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/0bfd8e6d4729c97745d3781a29610a33d0a8091d.1474003868.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
lib/syscall.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/lib/syscall.c b/lib/syscall.c
index e30e039..63239e0 100644
--- a/lib/syscall.c
+++ b/lib/syscall.c
@@ -7,9 +7,19 @@ static int collect_syscall(struct task_struct *target, long *callno,
unsigned long args[6], unsigned int maxargs,
unsigned long *sp, unsigned long *pc)
{
- struct pt_regs *regs = task_pt_regs(target);
- if (unlikely(!regs))
+ struct pt_regs *regs;
+
+ if (!try_get_task_stack(target)) {
+ /* Task has no stack, so the task isn't in a syscall. */
+ *callno = -1;
+ return 0;
+ }
+
+ regs = task_pt_regs(target);
+ if (unlikely(!regs)) {
+ put_task_stack(target);
return -EAGAIN;
+ }
*sp = user_stack_pointer(regs);
*pc = instruction_pointer(regs);
@@ -18,6 +28,7 @@ static int collect_syscall(struct task_struct *target, long *callno,
if (*callno != -1L && maxargs > 0)
syscall_get_arguments(target, regs, 0, maxargs, args);
+ put_task_stack(target);
return 0;
}
next prev parent reply other threads:[~2016-09-16 9:19 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-16 5:45 [PATCH v2 0/8] thread_info cleanups and stack caching Andy Lutomirski
2016-09-16 5:45 ` [PATCH v2 1/8] x86/entry/64: Fix a minor comment rebase error Andy Lutomirski
2016-09-16 9:16 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-09-16 5:45 ` [PATCH v2 2/8] sched: Add try_get_task_stack() and put_task_stack() Andy Lutomirski
2016-09-16 9:16 ` [tip:x86/asm] sched/core: " tip-bot for Andy Lutomirski
2016-09-16 5:45 ` [PATCH v2 3/8] kthread: to_live_kthread() needs try_get_task_stack() Andy Lutomirski
2016-09-16 9:17 ` [tip:x86/asm] kthread: Pin the stack via try_get_task_stack()/put_task_stack() in to_live_kthread() function tip-bot for Oleg Nesterov
2016-09-16 5:45 ` [PATCH v2 4/8] x86/dumpstack: Pin the target stack when dumping it Andy Lutomirski
2016-09-16 9:17 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-09-16 11:55 ` Josh Poimboeuf
2016-09-16 12:28 ` Josh Poimboeuf
2016-09-16 12:57 ` Ingo Molnar
2016-09-16 13:05 ` [PATCH] x86/dumpstack: remove NULL task pointer convention Josh Poimboeuf
2016-09-16 5:45 ` [PATCH v2 5/8] x86/process: Pin the target stack in get_wchan() Andy Lutomirski
2016-09-16 9:18 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-09-16 5:45 ` [PATCH v2 6/8] lib/syscall: Pin the task stack in collect_syscall() Andy Lutomirski
2016-09-16 9:18 ` tip-bot for Andy Lutomirski [this message]
2016-09-16 5:45 ` [PATCH v2 7/8] sched: Free the stack early if CONFIG_THREAD_INFO_IN_TASK Andy Lutomirski
2016-09-16 9:19 ` [tip:x86/asm] sched/core: " tip-bot for Andy Lutomirski
2016-09-16 5:45 ` [PATCH v2 8/8] fork: Cache two thread stacks per cpu if CONFIG_VMAP_STACK is set Andy Lutomirski
2016-09-16 9:19 ` [tip:x86/asm] fork: Optimize task creation by caching two thread stacks per CPU if CONFIG_VMAP_STACK=y tip-bot for Andy Lutomirski
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