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 11:23:10 +0200 |
| commit | db2baeef79d1d0ff0fac4589f8d7dc215ea36889 (patch) | |
| tree | 8f460402caa25af084578a0d95c4731a5ab11851 /kernel/printk | |
| parent | ca558fb836d3b04fbda144fa22e295d5f41bc2de (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/nmi.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/printk/nmi.c b/kernel/printk/nmi.c index 16bab471c7e2..5fa65aa904d3 100644 --- a/kernel/printk/nmi.c +++ b/kernel/printk/nmi.c @@ -63,6 +63,7 @@ static int vprintk_nmi(const char *fmt, va_list args) struct nmi_seq_buf *s = this_cpu_ptr(&nmi_print_seq); int add = 0; size_t len; + va_list ap; again: len = atomic_read(&s->len); @@ -79,7 +80,9 @@ again: if (!len) smp_rmb(); - add = vsnprintf(s->buffer + len, sizeof(s->buffer) - len, fmt, args); + va_copy(ap, args); + add = vsnprintf(s->buffer + len, sizeof(s->buffer) - len, fmt, ap); + va_end(ap); /* * Do it once again if the buffer has been flushed in the meantime. |