diff options
| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2018-05-11 19:54:19 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-07-03 11:24:49 +0200 |
| commit | a47c3c48769ab1e41f1dd53aa116a89f1f208aa1 (patch) | |
| tree | c6231ac2a7a7860dc2313e427dc37782c6090c8c /kernel/printk | |
| parent | affd84024cbedfc0ee091396d064fbf1366ea8fe (diff) | |
printk: fix possible reuse of va_list variable
commit 988a35f8da1dec5a8cd2788054d1e717be61bf25 upstream.
I noticed that there is a possibility that printk_safe_log_store() causes
kernel oops because "args" parameter is passed to vsnprintf() again when
atomic_cmpxchg() detected that we raced. Fix this by using va_copy().
Link: http://lkml.kernel.org/r/201805112002.GIF21216.OFVHFOMLJtQFSO@I-love.SAKURA.ne.jp
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: dvyukov@google.com
Cc: syzkaller@googlegroups.com
Cc: fengguang.wu@intel.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Fixes: 42a0bb3f71383b45 ("printk/nmi: generic solution for safe printk in NMI")
Cc: 4.7+ <stable@vger.kernel.org> # v4.7+
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/printk')
| -rw-r--r-- | kernel/printk/printk_safe.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c index 3cdaeaef9ce1..d989cc238198 100644 --- a/kernel/printk/printk_safe.c +++ b/kernel/printk/printk_safe.c @@ -85,6 +85,7 @@ static __printf(2, 0) int printk_safe_log_store(struct printk_safe_seq_buf *s, { int add; size_t len; + va_list ap; again: len = atomic_read(&s->len); @@ -103,7 +104,9 @@ again: if (!len) smp_rmb(); - add = vscnprintf(s->buffer + len, sizeof(s->buffer) - len, fmt, args); + va_copy(ap, args); + add = vscnprintf(s->buffer + len, sizeof(s->buffer) - len, fmt, ap); + va_end(ap); if (!add) return 0; |