kernel/linux.git/sound/core/seq, branch v6.1.168

ALSA: seq: Improve data consistency at polling

2025-06-04T12:40:08+00:00

[ Upstream commit e3cd33ab17c33bd8f1a9df66ec83a15dd8f7afbb ] snd_seq_poll() calls snd_seq_write_pool_allocated() that reads out a field in client->pool object, while it can be updated concurrently via ioctls, as reported by syzbot. The data race itself is harmless, as it's merely a poll() call, and the state is volatile. OTOH, the read out of poll object info from the caller side is fragile, and we can leave it better in snd_seq_pool_poll_wait() alone. A similar pattern is seen in snd_seq_kernel_client_write_poll(), too, which is called from the OSS sequencer. This patch drops the pool checks from the caller side and add the pool->lock in snd_seq_pool_poll_wait() for better data consistency. Reported-by: syzbot+2d373c9936c00d7e120c@syzkaller.appspotmail.com Closes: https://lore.kernel.org/67c88903.050a0220.15b4b9.0028.GAE@google.com Link: https://patch.msgid.link/20250307084246.29271-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: seq: oss: Fix races at processing SysEx messages

2025-01-09T12:30:05+00:00

commit 0179488ca992d79908b8e26b9213f1554fc5bacc upstream. OSS sequencer handles the SysEx messages split in 6 bytes packets, and ALSA sequencer OSS layer tries to combine those. It stores the data in the internal buffer and this access is racy as of now, which may lead to the out-of-bounds access. As a temporary band-aid fix, introduce a mutex for serializing the process of the SysEx message packets. Reported-by: Kun Hu Closes: https://lore.kernel.org/2B7E93E4-B13A-4AE4-8E87-306A8EE9BBB7@m.fudan.edu.cn Cc: Link: https://patch.msgid.link/20241230110543.32454-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: seq: fix function cast warnings

2024-03-26T22:20:48+00:00

[ Upstream commit d7bf73809849463f76de42aad62c850305dd6c5d ] clang-16 points out a control flow integrity (kcfi) issue when event callbacks get converted to incompatible types: sound/core/seq/seq_midi.c:135:30: error: cast from 'int (*)(struct snd_rawmidi_substream *, const char *, int)' to 'snd_seq_dump_func_t' (aka 'int (*)(void *, void *, int)') converts to incompatible function type [-Werror,-Wcast-function-type-strict] 135 | snd_seq_dump_var_event(ev, (snd_seq_dump_func_t)dump_midi, substream); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ sound/core/seq/seq_virmidi.c:83:31: error: cast from 'int (*)(struct snd_rawmidi_substream *, const unsigned char *, int)' to 'snd_seq_dump_func_t' (aka 'int (*)(void *, void *, int)') converts to incompatible function type [-Werror,-Wcast-function-type-strict] 83 | snd_seq_dump_var_event(ev, (snd_seq_dump_func_t)snd_rawmidi_receive, vmidi->substream); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For addressing those errors, introduce wrapper functions that are used for callbacks and bridge to the actual function call with pointer cast. The code was originally added with the initial ALSA merge in linux-2.5.4. [ the patch description shamelessly copied from Arnd's original patch -- tiwai ] Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Arnd Bergmann Link: https://lore.kernel.org/r/20240213101020.459183-1-arnd@kernel.org Link: https://lore.kernel.org/r/20240213135343.16411-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: seq: oss: Fix racy open/close of MIDI devices

2023-09-13T07:42:25+00:00

[ Upstream commit 297224fc0922e7385573a30c29ffdabb67f27b7d ] Although snd_seq_oss_midi_open() and snd_seq_oss_midi_close() can be called concurrently from different code paths, we have no proper data protection against races. Introduce open_mutex to each seq_oss_midi object for avoiding the races. Reported-by: "Gong, Sishuai" Closes: https://lore.kernel.org/r/7DC9AF71-F481-4ABA-955F-76C535661E33@purdue.edu Link: https://lore.kernel.org/r/20230612125533.27461-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: seq: Fix function prototype mismatch in snd_seq_expand_var_event

2022-11-19T08:20:11+00:00

With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG), indirect call targets are validated against the expected function pointer prototype to make sure the call target is valid to help mitigate ROP attacks. If they are not identical, there is a failure at run time, which manifests as either a kernel panic or thread getting killed. seq_copy_in_user() and seq_copy_in_kernel() did not have prototypes matching snd_seq_dump_func_t. Adjust this and remove the casts. There are not resulting binary output differences. This was found as a result of Clang's new -Wcast-function-type-strict flag, which is more sensitive than the simpler -Wcast-function-type, which only checks for type width mismatches. Reported-by: kernel test robot Link: https://lore.kernel.org/lkml/202211041527.HD8TLSE1-lkp@intel.com Cc: Jaroslav Kysela Cc: Takashi Iwai Cc: "Gustavo A. R. Silva" Cc: alsa-devel@alsa-project.org Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20221118232346.never.380-kees@kernel.org Signed-off-by: Takashi Iwai

ALSA: seq: Fix data-race at module auto-loading

2022-08-24T05:59:06+00:00

It's been reported that there is a possible data-race accessing to the global card_requested[] array at ALSA sequencer core, which is used for determining whether to call request_module() for the card or not. This data race itself is almost harmless, as it might end up with one extra request_module() call for the already loaded module at most. But it's still better to fix. This patch addresses the possible data race of card_requested[] and client_requested[] arrays by replacing them with bitmask. It's an atomic operation and can work without locks. Reported-by: Abhishek Shah Cc: Link: https://lore.kernel.org/r/CAEHB24_ay6YzARpA1zgCsE7=H9CSJJzux618E=Ka4h0YdKn=qA@mail.gmail.com Link: https://lore.kernel.org/r/20220823072717.1706-2-tiwai@suse.de Signed-off-by: Takashi Iwai

ALSA: seq: oss: Fix data-race for max_midi_devs access

2022-08-23T15:00:12+00:00

ALSA OSS sequencer refers to a global variable max_midi_devs at creating a new port, storing it to its own field. Meanwhile this variable may be changed by other sequencer events at snd_seq_oss_midi_check_exit_port() in parallel, which may cause a data race. OTOH, this data race itself is almost harmless, as the access to the MIDI device is done via get_mdev() and it's protected with a refcount, hence its presence is guaranteed. Though, it's sill better to address the data-race from the code sanity POV, and this patch adds the proper spinlock for the protection. Reported-by: Abhishek Shah Cc: Link: https://lore.kernel.org/r/CAEHB2493pZRXs863w58QWnUTtv3HHfg85aYhLn5HJHCwxqtHQg@mail.gmail.com Link: https://lore.kernel.org/r/20220823072717.1706-1-tiwai@suse.de Signed-off-by: Takashi Iwai

ALSA: seq: replace ternary operator with max()

2022-05-17T06:49:42+00:00

Fix the following coccicheck warning: sound/core/seq/seq_ports.c:142:12-14: WARNING opportunity for max() Signed-off-by: Guo Zhengkui Link: https://lore.kernel.org/r/20220517062518.123292-1-guozhengkui@vivo.com Signed-off-by: Takashi Iwai

ALSA: seq: oss: fix typo

2022-03-14T06:51:22+00:00

Fix typo in "announcement". Reported-by: Joe Perches Signed-off-by: Julia Lawall Link: https://lore.kernel.org/r/20220313085635.102123-1-Julia.Lawall@inria.fr Signed-off-by: Takashi Iwai

ALSA: seq: oss: use kzalloc

2022-03-13T08:09:37+00:00

Use kzalloc instead of kmalloc + memset. The semantic patch that makes this change is: (https://coccinelle.gitlabpages.inria.fr/website/) // @@ expression res, size, flag; @@ - res = kmalloc(size, flag); + res = kzalloc(size, flag); ... - memset(res, 0, size); // Signed-off-by: Julia Lawall Link: https://lore.kernel.org/r/20220312102705.71413-4-Julia.Lawall@inria.fr Signed-off-by: Takashi Iwai