From: Andrew Morton <akpm@linux-foundation.org>
To: Helge Deller <deller@gmx.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] proc/wchan: Use printk format instead of lookup_symbol_name()
Date: Tue, 22 Dec 2020 18:18:07 -0800 [thread overview]
Message-ID: <20201222181807.360cd9458d50b625608b8b44@linux-foundation.org> (raw)
In-Reply-To: <20201217165413.GA1959@ls3530.fritz.box>
On Thu, 17 Dec 2020 17:54:13 +0100 Helge Deller <deller@gmx.de> wrote:
> To resolve the symbol fuction name for wchan, use the printk format
> specifier %ps instead of manually looking up the symbol function name
> via lookup_symbol_name().
>
> Signed-off-by: Helge Deller <deller@gmx.de>
>
Please don't forget the "^---$" to separate the changelog from the
diff.
> #include <linux/module.h>
> @@ -386,19 +385,17 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
> struct pid *pid, struct task_struct *task)
> {
> unsigned long wchan;
> - char symname[KSYM_NAME_LEN];
>
> - if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
> - goto print0;
> + if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
> + wchan = get_wchan(task);
> + else
> + wchan = 0;
>
> - wchan = get_wchan(task);
> - if (wchan && !lookup_symbol_name(wchan, symname)) {
> - seq_puts(m, symname);
> - return 0;
> - }
> + if (wchan)
> + seq_printf(m, "%ps", (void *) wchan);
> + else
> + seq_putc(m, '0');
>
> -print0:
> - seq_putc(m, '0');
> return 0;
> }
We can simplify this further?
static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
seq_printf(m, "%ps", (void *)get_wchan(task));
else
seq_putc(m, '0');
return 0;
}
--- a/fs/proc/base.c~proc-wchan-use-printk-format-instead-of-lookup_symbol_name-fix
+++ a/fs/proc/base.c
@@ -384,15 +384,8 @@ static const struct file_operations proc
static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
- unsigned long wchan;
-
if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
- wchan = get_wchan(task);
- else
- wchan = 0;
-
- if (wchan)
- seq_printf(m, "%ps", (void *) wchan);
+ seq_printf(m, "%ps", (void *)get_wchan(task));
else
seq_putc(m, '0');
_
next prev parent reply other threads:[~2020-12-23 3:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-17 16:54 [PATCH] proc/wchan: Use printk format instead of lookup_symbol_name() Helge Deller
2020-12-23 2:18 ` Andrew Morton [this message]
2020-12-23 9:48 ` Helge Deller
2020-12-23 20:29 ` Andrew Morton
2021-01-03 14:27 ` [proc/wchan] 30a3a19273: leaking-addresses.proc.wchan./proc/bus/input/devices:B:KEY=1000000000007ff980000000007fffebeffdfffeffffffffffffffffffffe kernel test robot
2021-01-03 18:25 ` Helge Deller
2021-01-04 13:27 ` Oliver Sang
2021-09-24 1:01 ` /proc/$pid/chan kernel address exposures (was Re: [proc/wchan] 30a3a19273: leaking-addresses.proc.wchan./proc/bus/input/devices:B:KEY=1000000000007ff980000000007fffebeffdfffeffffffffffffffffffffe) Kees Cook
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