From: Masami Hiramatsu <mhiramat@kernel.org> To: Linus Torvalds <torvalds@linux-foundation.org> Cc: kernel test robot <lkp@intel.com>, Steven Rostedt <rostedt@goodmis.org>, Shuah Khan <shuah@kernel.org>, Linux List Kernel Mailing <linux-kernel@vger.kernel.org>, Andy Lutomirski <luto@amacapital.net>, Ingo Molnar <mingo@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Changbin Du <changbin.du@gmail.com>, Jann Horn <jannh@google.com>, Kees Cook <keescook@chromium.org>, Andy Lutomirski <luto@kernel.org>, Alexei Starovoitov <alexei.starovoitov@gmail.com>, Nadav Amit <namit@vmware.com>, Peter Zijlstra <peterz@infradead.org>, Joel Fernandes <joel@joelfernandes.org>, yhs@fb.com, lkp@01.org Subject: Re: [uaccess] 780464aed0: WARNING:at_arch/x86/include/asm/uaccess.h:#strnlen_user/0x Date: Mon, 4 Mar 2019 18:06:10 +0900 [thread overview] Message-ID: <20190304180610.2d4f6f08d9ad89d6abae3597@kernel.org> (raw) In-Reply-To: <CAHk-=whYMvevgF4yh7uhQug=Wt1A1Eg7abyM=RCi=bQiqiMBvQ@mail.gmail.com> On Sun, 3 Mar 2019 18:37:59 -0800 Linus Torvalds <torvalds@linux-foundation.org> wrote: > On Sun, Mar 3, 2019 at 5:14 PM Masami Hiramatsu <mhiramat@kernel.org> wrote: > > > > I think it comes from WARN_ON_ONCE(!segment_eq(get_fs(), USER_DS)) in > > user_access_ok(). The call trace shows that strndup_user might be called > > from kernel daemon context. > > Ahh, yes. > > We've had this before. We've gotten rid of the actual "use system > calls", but we still have some of the init sequence in particular just > calling the wrappers instead. Are those safe if we are in init sequence? > > And yes, ksys_mount() takes __user pointers. > > It would be a lot better to use "do_mount()", which is the interface > that takes actual "char *" pointers. Unfortunately, it still takes a __user pointer. long do_mount(const char *dev_name, const char __user *dir_name, const char *type_page, unsigned long flags, void *data_page) So what we need is long do_mount(const char *dev_name, struct path *dir_path, const char *type_page, unsigned long flags, void *data_page) or introduce kern_do_mount()? Since devtmpfsd calls ksys_chdir() and ksys_chroot(), we need to replace those too. Fortunately, it seems that the last part which we have to fix. Thank you, > > Linus -- Masami Hiramatsu <mhiramat@kernel.org>
WARNING: multiple messages have this Message-ID (diff)
From: Masami Hiramatsu <mhiramat@kernel.org> To: lkp@lists.01.org Subject: Re: [uaccess] 780464aed0: WARNING:at_arch/x86/include/asm/uaccess.h:#strnlen_user/0x Date: Mon, 04 Mar 2019 18:06:10 +0900 [thread overview] Message-ID: <20190304180610.2d4f6f08d9ad89d6abae3597@kernel.org> (raw) In-Reply-To: <CAHk-=whYMvevgF4yh7uhQug=Wt1A1Eg7abyM=RCi=bQiqiMBvQ@mail.gmail.com> [-- Attachment #1: Type: text/plain, Size: 1417 bytes --] On Sun, 3 Mar 2019 18:37:59 -0800 Linus Torvalds <torvalds@linux-foundation.org> wrote: > On Sun, Mar 3, 2019 at 5:14 PM Masami Hiramatsu <mhiramat@kernel.org> wrote: > > > > I think it comes from WARN_ON_ONCE(!segment_eq(get_fs(), USER_DS)) in > > user_access_ok(). The call trace shows that strndup_user might be called > > from kernel daemon context. > > Ahh, yes. > > We've had this before. We've gotten rid of the actual "use system > calls", but we still have some of the init sequence in particular just > calling the wrappers instead. Are those safe if we are in init sequence? > > And yes, ksys_mount() takes __user pointers. > > It would be a lot better to use "do_mount()", which is the interface > that takes actual "char *" pointers. Unfortunately, it still takes a __user pointer. long do_mount(const char *dev_name, const char __user *dir_name, const char *type_page, unsigned long flags, void *data_page) So what we need is long do_mount(const char *dev_name, struct path *dir_path, const char *type_page, unsigned long flags, void *data_page) or introduce kern_do_mount()? Since devtmpfsd calls ksys_chdir() and ksys_chroot(), we need to replace those too. Fortunately, it seems that the last part which we have to fix. Thank you, > > Linus -- Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2019-03-04 9:06 UTC|newest] Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-02-28 16:02 [PATCH v5 0/6] tracing/probes: uaccess: Add support user-space access Masami Hiramatsu 2019-02-28 16:02 ` [PATCH v5 1/6] uaccess: Add user_access_ok() Masami Hiramatsu 2019-02-28 16:03 ` [PATCH v5 2/6] uaccess: Use user_access_ok() in user_access_begin() Masami Hiramatsu 2019-03-03 17:39 ` [uaccess] 780464aed0: WARNING:at_arch/x86/include/asm/uaccess.h:#strnlen_user/0x kernel test robot 2019-03-03 17:39 ` kernel test robot 2019-03-03 19:53 ` Linus Torvalds 2019-03-03 19:53 ` Linus Torvalds 2019-03-04 1:14 ` Masami Hiramatsu 2019-03-04 1:14 ` Masami Hiramatsu 2019-03-04 2:37 ` Linus Torvalds 2019-03-04 2:37 ` Linus Torvalds 2019-03-04 9:06 ` Masami Hiramatsu [this message] 2019-03-04 9:06 ` Masami Hiramatsu 2019-03-04 15:16 ` Masami Hiramatsu 2019-03-04 15:16 ` Masami Hiramatsu 2019-03-04 15:58 ` Jann Horn 2019-03-04 15:58 ` Jann Horn 2019-03-04 18:59 ` Linus Torvalds 2019-03-04 18:59 ` Linus Torvalds 2019-03-05 2:36 ` Masami Hiramatsu 2019-03-05 2:36 ` Masami Hiramatsu 2019-03-05 8:22 ` Masami Hiramatsu 2019-03-05 8:22 ` Masami Hiramatsu 2019-03-05 9:01 ` Masami Hiramatsu 2019-03-05 9:01 ` Masami Hiramatsu 2019-03-05 9:07 ` Peter Zijlstra 2019-03-05 9:07 ` Peter Zijlstra 2019-03-05 13:58 ` Masami Hiramatsu 2019-03-05 13:58 ` Masami Hiramatsu 2019-03-05 14:53 ` Peter Zijlstra 2019-03-05 14:53 ` Peter Zijlstra 2019-03-05 15:18 ` Masami Hiramatsu 2019-03-05 15:18 ` Masami Hiramatsu 2019-03-04 3:20 ` [LKP] " Rong Chen 2019-03-04 3:20 ` Rong Chen 2019-02-28 16:03 ` [PATCH v5 3/6] uaccess: Add non-pagefault user-space read functions Masami Hiramatsu 2019-02-28 22:49 ` Yonghong Song 2019-03-01 2:29 ` Masami Hiramatsu 2019-03-01 6:30 ` Yonghong Song 2019-02-28 16:04 ` [PATCH v5 4/6] tracing/probe: Add ustring type for user-space string Masami Hiramatsu 2019-02-28 16:04 ` [PATCH v5 5/6] tracing/probe: Support user-space dereference Masami Hiramatsu 2019-02-28 16:05 ` [PATCH v5 6/6] selftests/ftrace: Add user-memory access syntax testcase Masami Hiramatsu
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