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authorKees Cook <keescook@chromium.org>2021-09-30 01:02:13 +0300
committerPeter Zijlstra <peterz@infradead.org>2021-10-15 12:25:13 +0300
commit54354c6a9f7fd5572d2b9ec108117c4f376d4d23 (patch)
tree1d22cf0cdb4c60371387f17d2f4eabdaef7806cb /fs/proc
parent804bccba71a57e7e5deb507a4c8ebbab730909c0 (diff)
downloadlinux-54354c6a9f7fd5572d2b9ec108117c4f376d4d23.tar.xz
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
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/base.c19
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 */