diff options
| author | Kees Cook | 2021-09-29 15:02:13 -0700 |
|---|---|---|
| committer | Peter Zijlstra | 2021-10-15 11:25:13 +0200 |
| commit | 54354c6a9f7fd5572d2b9ec108117c4f376d4d23 (patch) | |
| tree | 1d22cf0cdb4c60371387f17d2f4eabdaef7806cb | |
| parent | 804bccba71a57e7e5deb507a4c8ebbab730909c0 (diff) | |
Revert "proc/wchan: use printk format instead of lookup_symbol_name()"
This reverts commit 152c432b128cb043fc107e8f211195fe94b2159c.
When a kernel address couldn't be symbolized for /proc/$pid/wchan, it
would leak the raw value, a potential information exposure. This is a
regression compared to the safer pre-v5.12 behavior.
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: Vito Caputo <vcaputo@pengaru.com>
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20211008111626.090829198@infradead.org
| -rw-r--r-- | fs/proc/base.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 533d5836eb9a..1f394095eb88 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -67,6 +67,7 @@ #include <linux/mm.h> #include <linux/swap.h> #include <linux/rcupdate.h> +#include <linux/kallsyms.h> #include <linux/stacktrace.h> #include <linux/resource.h> #include <linux/module.h> @@ -386,17 +387,19 @@ 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)) - wchan = get_wchan(task); - else - wchan = 0; + if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) + goto print0; - if (wchan) - seq_printf(m, "%ps", (void *) wchan); - else - seq_putc(m, '0'); + wchan = get_wchan(task); + if (wchan && !lookup_symbol_name(wchan, symname)) { + seq_puts(m, symname); + return 0; + } +print0: + seq_putc(m, '0'); return 0; } #endif /* CONFIG_KALLSYMS */ |