3.16.78-rc1 review patch. If anyone has any objections, please let me know.
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From: Takashi Iwai tiwai@suse.de
commit 75545304eba6a3d282f923b96a466dc25a81e359 upstream.
The input pool of a client might be deleted via the resize ioctl, the the access to it should be covered by the proper locks. Currently the only missing place is the call in snd_seq_ioctl_get_client_pool(), and this patch papers over it.
Reported-by: syzbot+4a75454b9ca2777f35c7@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai tiwai@suse.de [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- sound/core/seq/seq_clientmgr.c | 3 +-- sound/core/seq/seq_fifo.c | 17 +++++++++++++++++ sound/core/seq/seq_fifo.h | 2 ++ 3 files changed, 20 insertions(+), 2 deletions(-)
--- a/sound/core/seq/seq_clientmgr.c +++ b/sound/core/seq/seq_clientmgr.c @@ -1911,8 +1911,7 @@ static int snd_seq_ioctl_get_client_pool if (cptr->type == USER_CLIENT) { info.input_pool = cptr->data.user.fifo_pool_size; info.input_free = info.input_pool; - if (cptr->data.user.fifo) - info.input_free = snd_seq_unused_cells(cptr->data.user.fifo->pool); + info.input_free = snd_seq_fifo_unused_cells(cptr->data.user.fifo); } else { info.input_pool = 0; info.input_free = 0; --- a/sound/core/seq/seq_fifo.c +++ b/sound/core/seq/seq_fifo.c @@ -278,3 +278,20 @@ int snd_seq_fifo_resize(struct snd_seq_f
return 0; } + +/* get the number of unused cells safely */ +int snd_seq_fifo_unused_cells(struct snd_seq_fifo *f) +{ + unsigned long flags; + int cells; + + if (!f) + return 0; + + snd_use_lock_use(&f->use_lock); + spin_lock_irqsave(&f->lock, flags); + cells = snd_seq_unused_cells(f->pool); + spin_unlock_irqrestore(&f->lock, flags); + snd_use_lock_free(&f->use_lock); + return cells; +} --- a/sound/core/seq/seq_fifo.h +++ b/sound/core/seq/seq_fifo.h @@ -68,5 +68,7 @@ int snd_seq_fifo_poll_wait(struct snd_se /* resize pool in fifo */ int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize);
+/* get the number of unused cells safely */ +int snd_seq_fifo_unused_cells(struct snd_seq_fifo *f);
#endif