fe08f34d06
syzkaller triggered kernel warnings through PCM OSS emulation at closing a stream: WARNING: CPU: 0 PID: 3502 at sound/core/pcm_lib.c:1635 snd_pcm_hw_param_first+0x289/0x690 sound/core/pcm_lib.c:1635 Call Trace: .... snd_pcm_hw_param_near.constprop.27+0x78d/0x9a0 sound/core/oss/pcm_oss.c:457 snd_pcm_oss_change_params+0x17d3/0x3720 sound/core/oss/pcm_oss.c:969 snd_pcm_oss_make_ready+0xaa/0x130 sound/core/oss/pcm_oss.c:1128 snd_pcm_oss_sync+0x257/0x830 sound/core/oss/pcm_oss.c:1638 snd_pcm_oss_release+0x20b/0x280 sound/core/oss/pcm_oss.c:2431 __fput+0x327/0x7e0 fs/file_table.c:210 .... This happens while it tries to open and set up the aloop device concurrently. The warning above (invoked from snd_BUG_ON() macro) is to detect the unexpected logical error where snd_pcm_hw_refine() call shouldn't fail. The theory is true for the case where the hw_params config rules are static. But for an aloop device, the hw_params rule condition does vary dynamically depending on the connected target; when another device is opened and changes the parameters, the device connected in another side is also affected, and it caused the error from snd_pcm_hw_refine(). That is, the simplest "solution" for this is to remove the incorrect assumption of static rules, and treat such an error as a normal error path. As there are a couple of other places using snd_BUG_ON() incorrectly, this patch removes these spurious snd_BUG_ON() calls. Reported-by: syzbot+6f11c7e2a1b91d466432@syzkaller.appspotmail.com Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.