lkml.org 
[lkml]   [2011]   [May]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:perf/urgent] powerpc, hw_breakpoints: Fix racy access to ptrace breakpoints
Commit-ID:  07fa7a0a8a586c01a8b416358c7012dcb9dc688d
Gitweb: http://git.kernel.org/tip/07fa7a0a8a586c01a8b416358c7012dcb9dc688d
Author: Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Fri, 8 Apr 2011 17:29:36 +0200
Committer: Frederic Weisbecker <fweisbec@gmail.com>
CommitDate: Mon, 25 Apr 2011 17:33:54 +0200

powerpc, hw_breakpoints: Fix racy access to ptrace breakpoints

While the tracer accesses ptrace breakpoints, the child task may
concurrently exit due to a SIGKILL and thus release its breakpoints
at the same time. We can then dereference some freed pointers.

To fix this, hold a reference on the child breakpoints before
manipulating them.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Prasad <prasad@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: v2.6.33.. <stable@kernel.org>
Link: http://lkml.kernel.org/r/1302284067-7860-4-git-send-email-fweisbec@gmail.com
---
arch/powerpc/kernel/ptrace.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 55613e3..4edeeb3 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -1591,7 +1591,10 @@ long arch_ptrace(struct task_struct *child, long request,
}

case PTRACE_SET_DEBUGREG:
+ if (ptrace_get_breakpoints(child) < 0)
+ return -ESRCH;
ret = ptrace_set_debugreg(child, addr, data);
+ ptrace_put_breakpoints(child);
break;

#ifdef CONFIG_PPC64

\
 
 \ /
  Last update: 2011-05-04 22:33    [from the cache]
©2003-2011 Jasper Spaans