From: Al Viro <viro@xxxxxxxxxxxxxxxxxx> ... and no, __put_user() doesn't help here - skipping access_ok() on the second call does not remove the possibility of page having become unmapped or r/o in the meanwhile Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> --- sound/core/pcm_native.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index aef860256278..47838f57a647 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -3093,7 +3093,8 @@ static int snd_pcm_xferi_frames_ioctl(struct snd_pcm_substream *substream, result = snd_pcm_lib_write(substream, xferi.buf, xferi.frames); else result = snd_pcm_lib_read(substream, xferi.buf, xferi.frames); - __put_user(result, &_xferi->result); + if (put_user(result, &_xferi->result)) + return -EFAULT; return result < 0 ? result : 0; } @@ -3122,7 +3123,8 @@ static int snd_pcm_xfern_frames_ioctl(struct snd_pcm_substream *substream, else result = snd_pcm_lib_readv(substream, bufs, xfern.frames); kfree(bufs); - __put_user(result, &_xfern->result); + if (put_user(result, &_xfern->result)) + return -EFAULT; return result < 0 ? result : 0; } @@ -3137,7 +3139,8 @@ static int snd_pcm_rewind_ioctl(struct snd_pcm_substream *substream, if (put_user(0, _frames)) return -EFAULT; result = snd_pcm_rewind(substream, frames); - __put_user(result, _frames); + if (put_user(result, _frames)) + return -EFAULT; return result < 0 ? result : 0; } @@ -3152,7 +3155,8 @@ static int snd_pcm_forward_ioctl(struct snd_pcm_substream *substream, if (put_user(0, _frames)) return -EFAULT; result = snd_pcm_forward(substream, frames); - __put_user(result, _frames); + if (put_user(result, _frames)) + return -EFAULT; return result < 0 ? result : 0; } -- 2.11.0
