From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org
Cc: Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org, Brian Gerst <brgerst@gmail.com>,
Jann Horn <jann@thejh.net>, Andy Lutomirski <luto@kernel.org>
Subject: [PATCH 10/12] lib/syscall: Pin the task stack in collect_syscall()
Date: Tue, 13 Sep 2016 14:29:30 -0700 [thread overview]
Message-ID: <5b241e82b85e4ecc757f29ae92355064963d9fef.1473801993.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1473801993.git.luto@kernel.org>
In-Reply-To: <cover.1473801993.git.luto@kernel.org>
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>
---
lib/syscall.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/lib/syscall.c b/lib/syscall.c
index e30e03932480..63239e097b13 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;
}
--
2.7.4
next prev parent reply other threads:[~2016-09-13 21:29 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-13 21:29 [PATCH 00/12] thread_info cleanups and stack caching Andy Lutomirski
2016-09-13 21:29 ` [PATCH 01/12] x86/asm: Move 'status' from struct thread_info to struct thread_struct Andy Lutomirski
2016-09-15 10:41 ` [tip:x86/asm] x86/asm: Move the thread_info::status field to thread_struct tip-bot for Andy Lutomirski
2016-09-13 21:29 ` [PATCH 02/12] x86/entry: Get rid of pt_regs_to_thread_info() Andy Lutomirski
2016-09-15 6:21 ` Ingo Molnar
2016-09-15 10:42 ` [tip:x86/asm] " tip-bot for Linus Torvalds
2016-09-13 21:29 ` [PATCH 03/12] um: Stop conflating task_struct::stack with thread_info Andy Lutomirski
2016-09-15 6:21 ` Ingo Molnar
2016-09-15 10:42 ` [tip:x86/asm] um/Stop " tip-bot for Linus Torvalds
2016-09-13 21:29 ` [PATCH 04/12] sched: Allow putting thread_info into task_struct Andy Lutomirski
2016-09-15 10:43 ` [tip:x86/asm] sched/core: " tip-bot for Andy Lutomirski
2016-09-13 21:29 ` [PATCH 05/12] x86: Move " Andy Lutomirski
2016-09-15 10:43 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-09-13 21:29 ` [PATCH 06/12] sched: Add try_get_task_stack() and put_task_stack() Andy Lutomirski
2016-09-13 21:29 ` [PATCH 07/12] kthread: to_live_kthread() needs try_get_task_stack() Andy Lutomirski
2016-09-13 21:29 ` [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Andy Lutomirski
2016-09-14 14:55 ` Josh Poimboeuf
2016-09-14 18:22 ` Andy Lutomirski
2016-09-14 18:35 ` Josh Poimboeuf
2016-09-15 18:04 ` Andy Lutomirski
2016-09-15 18:37 ` Josh Poimboeuf
2016-09-15 18:41 ` Andy Lutomirski
2016-09-15 19:19 ` Josh Poimboeuf
2016-09-16 7:47 ` Peter Zijlstra
2016-09-16 15:12 ` Andy Lutomirski
2016-09-16 15:31 ` Peter Zijlstra
2016-09-16 15:32 ` Andy Lutomirski
2016-09-16 16:35 ` Peter Zijlstra
2016-09-15 6:37 ` Ingo Molnar
[not found] ` <CA+55aFxt=HLrELBE=BXUrWdh6LYs4gtu9S=yCruiDffq4HN80w@mail.gmail.com>
2016-09-15 9:27 ` Ingo Molnar
2016-09-13 21:29 ` [PATCH 09/12] x86/process: Pin the target stack in get_wchan() Andy Lutomirski
2016-09-17 2:00 ` Jann Horn
2016-09-22 22:44 ` Andy Lutomirski
2016-09-22 22:50 ` Andy Lutomirski
2016-09-23 7:43 ` Jann Horn
2016-09-23 18:28 ` Kees Cook
2016-09-23 18:34 ` Jann Horn
2016-09-26 5:10 ` Tycho Andersen
2016-09-13 21:29 ` Andy Lutomirski [this message]
2016-09-13 21:29 ` [PATCH 11/12] sched: Free the stack early if CONFIG_THREAD_INFO_IN_TASK Andy Lutomirski
2016-09-13 21:29 ` [PATCH 12/12] fork: Cache two thread stacks per cpu if CONFIG_VMAP_STACK is set Andy Lutomirski
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