From: Jann Horn jannh@google.com
commit 1448769c9cdb69ad65287f4f7ab58bc5f2f5d7ba upstream.
signal_pending() checks TIF_NOTIFY_SIGNAL and TIF_SIGPENDING, which signal that the task should bail out of the syscall when possible. This is a separate concept from need_resched(), which checks TIF_NEED_RESCHED, signaling that the task should preempt.
In particular, with the current code, the signal_pending() bailout probably won't work reliably.
Change this to look like other functions that read lots of data, such as read_zero().
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Jann Horn jannh@google.com Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/char/random.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -550,13 +550,13 @@ static ssize_t get_random_bytes_user(voi }
do { - if (large_request && need_resched()) { + if (large_request) { if (signal_pending(current)) { if (!ret) ret = -ERESTARTSYS; break; } - schedule(); + cond_resched(); }
chacha20_block(chacha_state, output);