Re: Fwd: Potential out-of-bounds in ftrace_regex_release

From: Dave Jones <davej@redhat.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: linux-kernel@vger.kernel.org, rostedt@goodmis.org,
	fweisbec@gmail.com, mingo@redhat.com,
	Dmitry Vyukov <dvyukov@google.com>,
	Kostya Serebryany <kcc@google.com>
Subject: Re: Fwd: Potential out-of-bounds in ftrace_regex_release
Date: Wed, 2 Oct 2013 14:57:23 -0400	[thread overview]
Message-ID: <20131002185723.GA32614@redhat.com> (raw)
In-Reply-To: <CAAeHK+wy+vs2PniKh8DbWzZoS99g1eZ-U3mv+6SzoznC8WHW6A@mail.gmail.com>

On Wed, Oct 02, 2013 at 10:38:01PM +0400, Andrey Konovalov wrote:
 > Hi!
 > 
 > I am working on AddressSanitizer -- a tool that detects use-after-free
 > and out-of-bounds bugs
 > (https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel).
 > Below is one of the bug reports that I got while running trinity syscall fuzzer.
 > Kernel is built on revision d8efd82eece89f8a5790b0febf17522affe9e1f1.
 > 
 > [  286.473434] ERROR: AddressSanitizer: heap-buffer-overflow on
 > address ffff8800359c99f3
 > [  286.474598] ffff8800359c99f3 is located 0 bytes to the right of
 > 243-byte region [ffff8800359c9900, ffff8800359c99f3)
 > [  286.476100] Accessed by thread T13003:
 > [  286.476735]   #0 ffffffff810dd2da (asan_report_error+0x32a/0x440)
 > [  286.477556]   #1 ffffffff810dc6b0 (asan_check_region+0x30/0x40)
 > [  286.478353]   #2 ffffffff810dd4d3 (__tsan_write1+0x13/0x20)
 > [  286.479112]   #3 ffffffff811cd19e (ftrace_regex_release+0x1be/0x260)
 > [  286.479929]   #4 ffffffff812a1065 (__fput+0x155/0x360)
 > [  286.480627]   #5 ffffffff812a12de (____fput+0x1e/0x30)
 > [  286.481331]   #6 ffffffff8111708d (task_work_run+0x10d/0x140)
 > [  286.482107]   #7 ffffffff810ea043 (do_exit+0x433/0x11f0)
 > [  286.482793]   #8 ffffffff810eaee4 (do_group_exit+0x84/0x130)
 > [  286.483552]   #9 ffffffff810eafb1 (SyS_exit_group+0x21/0x30)
 > [  286.484320]   #10 ffffffff81928782 (system_call_fastpath+0x16/0x1b)
 > [  286.485151]

Excellent! This looks exactly like the trace I've been hitting that triggers
WARNING: CPU: 3 PID: 26435 at kernel/trace/ftrace.c:1640 __ftrace_hash_rec_update.part.37+0x20a/0x240()

 > [  286.485365] Allocated by thread T5167:
 > [  286.485979]   #0 ffffffff810dc778 (asan_slab_alloc+0x48/0xc0)
 > [  286.486750]   #1 ffffffff8128337c (__kmalloc+0xbc/0x500)
 > [  286.487474]   #2 ffffffff811d9d54 (trace_parser_get_init+0x34/0x90)
 > [  286.488313]   #3 ffffffff811cd7b3 (ftrace_regex_open+0x83/0x2e0)
 > [  286.489120]   #4 ffffffff811cda7d (ftrace_filter_open+0x2d/0x40)
 > [  286.489894]   #5 ffffffff8129b4ff (do_dentry_open+0x32f/0x430)
 > [  286.490674]   #6 ffffffff8129b668 (finish_open+0x68/0xa0)
 > [  286.491411]   #7 ffffffff812b66ac (do_last+0xb8c/0x1710)
 > [  286.492135]   #8 ffffffff812b7350 (path_openat+0x120/0xb50)
 > [  286.492855]   #9 ffffffff812b8884 (do_filp_open+0x54/0xb0)
 > [  286.493604]   #10 ffffffff8129d36c (do_sys_open+0x1ac/0x2c0)
 > [  286.494366]   #11 ffffffff8129d4b7 (SyS_open+0x37/0x50)
 > [  286.495078]   #12 ffffffff81928782 (system_call_fastpath+0x16/0x1b)

And that's the cause. I wonder what was being opened.
Do you happen to have a trinity-child log for that thread ?

	Dave