syzbot found that a thread can stall for minutes inside read_mem() after that thread was killed by SIGKILL [1]. Reading 2GB at one read() is legal, but delaying termination of killed thread for minutes is bad.
[ 1335.912419][T20577] read_mem: sz=4096 count=2134565632 [ 1335.943194][T20577] read_mem: sz=4096 count=2134561536 [ 1335.978280][T20577] read_mem: sz=4096 count=2134557440 [ 1336.011147][T20577] read_mem: sz=4096 count=2134553344 [ 1336.041897][T20577] read_mem: sz=4096 count=2134549248 [1] https://syzkaller.appspot.com/bug?id=a0e3436829698d5824231251fad9d8e998f94f5e Signed-off-by: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> Reported-by: syzbot <syzbot+8ab2d0f39fb79fe6c...@syzkaller.appspotmail.com> --- drivers/char/mem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index b08dc50..0f7d4c4 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -135,7 +135,7 @@ static ssize_t read_mem(struct file *file, char __user *buf, if (!bounce) return -ENOMEM; - while (count > 0) { + while (count > 0 && !fatal_signal_pending(current)) { unsigned long remaining; int allowed, probe; -- 1.8.3.1
