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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2018-05-11 19:54:19 +0900
committerPetr Mladek <pmladek@suse.com>2018-05-16 14:00:46 +0200
commit988a35f8da1dec5a8cd2788054d1e717be61bf25 (patch)
treee925f33580d5c761c0fe4bbe6eebb4a089eed20d /kernel/printk/printk_safe.c
parent43a17111c2553925f65e7be9b9c3f9d90cf29a8b (diff)
printk: fix possible reuse of va_list variable
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>
Diffstat (limited to 'kernel/printk/printk_safe.c')
-rw-r--r--kernel/printk/printk_safe.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index 3e3c2004bb23..449d67edfa4b 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -82,6 +82,7 @@ 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);
@@ -100,7 +101,9 @@ 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;