From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
Andy Lutomirski <luto@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
stable <stable@vger.kernel.org>,
Changbin Du <changbin.du@gmail.com>, Jann Horn <jannh@google.com>,
Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH 1/2 v2] kprobe: Do not use uaccess functions to access kernel memory that can fault
Date: Mon, 25 Feb 2019 09:33:09 +0100 [thread overview]
Message-ID: <20190225083309.GI32477@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAHk-=wjBD+MQfWP2Q4Zp8FP4HR4MdPACw1=iMbDZANdiBwXDAQ@mail.gmail.com>
On Sun, Feb 24, 2019 at 09:26:45AM -0800, Linus Torvalds wrote:
> PeterZ, do you remember the particular use case that triggered that
> commit 7c4788950ba5 ("x86/uaccess, sched/preempt: Verify access_ok()
> context")?
This one, if I'm not mistaken.
---
commit ae31fe51a3cceaa0cabdb3058f69669ecb47f12e
Author: Johannes Weiner <hannes@cmpxchg.org>
Date: Tue Nov 22 10:57:42 2016 +0100
perf/x86: Restore TASK_SIZE check on frame pointer
The following commit:
75925e1ad7f5 ("perf/x86: Optimize stack walk user accesses")
... switched from copy_from_user_nmi() to __copy_from_user_nmi() with a manual
access_ok() check.
Unfortunately, copy_from_user_nmi() does an explicit check against TASK_SIZE,
whereas the access_ok() uses whatever the current address limit of the task is.
We are getting NMIs when __probe_kernel_read() has switched to KERNEL_DS, and
then see vmalloc faults when we access what looks like pointers into vmalloc
space:
[] WARNING: CPU: 3 PID: 3685731 at arch/x86/mm/fault.c:435 vmalloc_fault+0x289/0x290
[] CPU: 3 PID: 3685731 Comm: sh Tainted: G W 4.6.0-5_fbk1_223_gdbf0f40 #1
[] Call Trace:
[] <NMI> [<ffffffff814717d1>] dump_stack+0x4d/0x6c
[] [<ffffffff81076e43>] __warn+0xd3/0xf0
[] [<ffffffff81076f2d>] warn_slowpath_null+0x1d/0x20
[] [<ffffffff8104a899>] vmalloc_fault+0x289/0x290
[] [<ffffffff8104b5a0>] __do_page_fault+0x330/0x490
[] [<ffffffff8104b70c>] do_page_fault+0xc/0x10
[] [<ffffffff81794e82>] page_fault+0x22/0x30
[] [<ffffffff81006280>] ? perf_callchain_user+0x100/0x2a0
[] [<ffffffff8115124f>] get_perf_callchain+0x17f/0x190
[] [<ffffffff811512c7>] perf_callchain+0x67/0x80
[] [<ffffffff8114e750>] perf_prepare_sample+0x2a0/0x370
[] [<ffffffff8114e840>] perf_event_output+0x20/0x60
[] [<ffffffff8114aee7>] ? perf_event_update_userpage+0xc7/0x130
[] [<ffffffff8114ea01>] __perf_event_overflow+0x181/0x1d0
[] [<ffffffff8114f484>] perf_event_overflow+0x14/0x20
[] [<ffffffff8100a6e3>] intel_pmu_handle_irq+0x1d3/0x490
[] [<ffffffff8147daf7>] ? copy_user_enhanced_fast_string+0x7/0x10
[] [<ffffffff81197191>] ? vunmap_page_range+0x1a1/0x2f0
[] [<ffffffff811972f1>] ? unmap_kernel_range_noflush+0x11/0x20
[] [<ffffffff814f2056>] ? ghes_copy_tofrom_phys+0x116/0x1f0
[] [<ffffffff81040d1d>] ? x2apic_send_IPI_self+0x1d/0x20
[] [<ffffffff8100411d>] perf_event_nmi_handler+0x2d/0x50
[] [<ffffffff8101ea31>] nmi_handle+0x61/0x110
[] [<ffffffff8101ef94>] default_do_nmi+0x44/0x110
[] [<ffffffff8101f13b>] do_nmi+0xdb/0x150
[] [<ffffffff81795187>] end_repeat_nmi+0x1a/0x1e
[] [<ffffffff8147daf7>] ? copy_user_enhanced_fast_string+0x7/0x10
[] [<ffffffff8147daf7>] ? copy_user_enhanced_fast_string+0x7/0x10
[] [<ffffffff8147daf7>] ? copy_user_enhanced_fast_string+0x7/0x10
[] <<EOE>> <IRQ> [<ffffffff8115d05e>] ? __probe_kernel_read+0x3e/0xa0
Fix this by moving the valid_user_frame() check to before the uaccess
that loads the return address and the pointer to the next frame.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org
Fixes: 75925e1ad7f5 ("perf/x86: Optimize stack walk user accesses")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index d31735f37ed7..9d4bf3ab049e 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2352,7 +2352,7 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
frame.next_frame = 0;
frame.return_address = 0;
- if (!access_ok(VERIFY_READ, fp, 8))
+ if (!valid_user_frame(fp, sizeof(frame)))
break;
bytes = __copy_from_user_nmi(&frame.next_frame, fp, 4);
@@ -2362,9 +2362,6 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
if (bytes != 0)
break;
- if (!valid_user_frame(fp, sizeof(frame)))
- break;
-
perf_callchain_store(entry, cs_base + frame.return_address);
fp = compat_ptr(ss_base + frame.next_frame);
}
@@ -2413,7 +2410,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
frame.next_frame = NULL;
frame.return_address = 0;
- if (!access_ok(VERIFY_READ, fp, sizeof(*fp) * 2))
+ if (!valid_user_frame(fp, sizeof(frame)))
break;
bytes = __copy_from_user_nmi(&frame.next_frame, fp, sizeof(*fp));
@@ -2423,9 +2420,6 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
if (bytes != 0)
break;
- if (!valid_user_frame(fp, sizeof(frame)))
- break;
-
perf_callchain_store(entry, frame.return_address);
fp = (void __user *)frame.next_frame;
}
next prev parent reply other threads:[~2019-02-25 8:33 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-15 17:47 [PATCH 0/2 v2] [GIT PULL (take two)] tracing: Two more fixes Steven Rostedt
2019-02-15 17:47 ` [PATCH 1/2 v2] kprobe: Do not use uaccess functions to access kernel memory that can fault Steven Rostedt
2019-02-15 17:55 ` Linus Torvalds
2019-02-15 22:15 ` Steven Rostedt
2019-02-15 23:49 ` Andy Lutomirski
2019-02-16 0:19 ` Steven Rostedt
2019-02-16 1:32 ` Andy Lutomirski
2019-02-16 2:08 ` Steven Rostedt
2019-02-16 2:14 ` Andy Lutomirski
2019-02-16 2:21 ` Steven Rostedt
2019-02-18 17:58 ` Linus Torvalds
2019-02-18 18:23 ` Linus Torvalds
2019-02-19 16:18 ` Steven Rostedt
2019-02-19 18:43 ` Linus Torvalds
2019-02-19 19:03 ` Steven Rostedt
2019-02-20 8:10 ` Masami Hiramatsu
2019-02-20 13:57 ` Jann Horn
2019-02-20 14:47 ` Steven Rostedt
2019-02-20 15:08 ` Masami Hiramatsu
2019-02-20 14:49 ` Steven Rostedt
2019-02-20 16:04 ` Masami Hiramatsu
2019-02-20 16:42 ` Steven Rostedt
2019-02-21 7:37 ` Masami Hiramatsu
2019-02-22 8:27 ` Masami Hiramatsu
2019-02-22 8:35 ` Masami Hiramatsu
2019-02-22 17:43 ` Linus Torvalds
2019-02-22 17:48 ` Andy Lutomirski
2019-02-22 18:28 ` Linus Torvalds
2019-02-22 19:52 ` Andy Lutomirski
2019-02-22 19:27 ` Alexei Starovoitov
2019-02-22 19:30 ` Steven Rostedt
2019-02-22 19:34 ` Alexei Starovoitov
2019-02-22 19:39 ` Steven Rostedt
2019-02-22 19:55 ` Andy Lutomirski
2019-02-22 21:43 ` Jann Horn
2019-02-22 22:08 ` Nadav Amit
2019-02-22 22:17 ` Jann Horn
2019-02-22 22:21 ` Nadav Amit
2019-02-22 22:39 ` Nadav Amit
2019-02-22 23:02 ` Jann Horn
2019-02-22 23:22 ` Nadav Amit
2019-02-22 23:59 ` Andy Lutomirski
2019-02-23 0:03 ` Alexei Starovoitov
2019-02-23 0:15 ` Nadav Amit
2019-02-24 19:35 ` Andy Lutomirski
2019-02-25 13:36 ` Masami Hiramatsu
2019-02-22 21:20 ` Linus Torvalds
2019-02-22 21:38 ` David Miller
2019-02-22 21:59 ` Linus Torvalds
2019-02-22 22:51 ` Alexei Starovoitov
2019-02-22 23:11 ` Jann Horn
2019-02-22 23:16 ` David Miller
2019-02-22 23:16 ` Linus Torvalds
2019-02-22 23:56 ` Alexei Starovoitov
2019-02-23 0:08 ` Linus Torvalds
2019-02-23 2:28 ` Alexei Starovoitov
2019-02-23 2:32 ` Linus Torvalds
2019-02-23 3:02 ` Steven Rostedt
2019-02-23 4:51 ` Masami Hiramatsu
2019-02-26 3:57 ` Christoph Hellwig
2019-02-26 15:24 ` Joel Fernandes
2019-02-28 12:29 ` Masami Hiramatsu
2019-02-28 15:18 ` Joel Fernandes
2019-02-23 3:47 ` Masami Hiramatsu
2019-02-24 0:44 ` Steven Rostedt
2019-02-24 4:38 ` Andy Lutomirski
2019-02-24 15:17 ` Masami Hiramatsu
2019-02-24 17:26 ` Linus Torvalds
2019-02-25 2:40 ` Masami Hiramatsu
2019-02-25 4:49 ` Andy Lutomirski
2019-02-25 8:09 ` Masami Hiramatsu
2019-02-25 16:40 ` Steven Rostedt
2019-02-26 1:35 ` Masami Hiramatsu
2019-02-25 8:33 ` Peter Zijlstra [this message]
2019-02-25 14:52 ` Peter Zijlstra
2019-02-25 16:48 ` Kees Cook
2019-02-25 16:58 ` Andy Lutomirski
2019-02-25 17:07 ` Kees Cook
2019-02-21 7:52 ` Masami Hiramatsu
2019-02-21 14:36 ` Steven Rostedt
2019-02-21 15:58 ` Masami Hiramatsu
2019-02-21 16:16 ` Masami Hiramatsu
2019-02-21 16:32 ` Steven Rostedt
2019-02-23 14:48 ` Masami Hiramatsu
2019-02-15 17:47 ` [PATCH 2/2 v2] tracing: Fix number of entries in trace header Steven Rostedt
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=20190225083309.GI32477@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=changbin.du@gmail.com \
--cc=jannh@google.com \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mhiramat@kernel.org \
--cc=mingo@kernel.org \
--cc=rostedt@goodmis.org \
--cc=stable@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
/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;
as well as URLs for NNTP newsgroup(s).