From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] proc: check permissions earlier for /proc/*/wchan
Date: Sat, 17 Feb 2018 10:19:24 +0300 [thread overview]
Message-ID: <20180217071923.GA16074@avx2> (raw)
get_wchan() accesses stack page before permissions are checked,
let's not play this game.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
fs/proc/base.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -391,14 +391,17 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
unsigned long wchan;
char symname[KSYM_NAME_LEN];
- wchan = get_wchan(task);
+ if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
+ goto print0;
- if (wchan && ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)
- && !lookup_symbol_name(wchan, symname))
+ wchan = get_wchan(task);
+ if (wchan && !lookup_symbol_name(wchan, symname)) {
seq_printf(m, "%s", symname);
- else
- seq_putc(m, '0');
+ return 0;
+ }
+print0:
+ seq_putc(m, '0');
return 0;
}
#endif /* CONFIG_KALLSYMS */
reply other threads:[~2018-02-17 7:19 UTC|newest]
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