From: Takashi Iwai <tiwai@suse.de> stable inclusion from stable-v5.10.142 commit 1079d095725a66c3c45274cb62ebf1f29759c780 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6CSFH Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 3e7e04b747adea36f349715d9f0998eeebf15d72 upstream. 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 <abhishek.shah@columbia.edu> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/CAEHB24_ay6YzARpA1zgCsE7=H9CSJJzux618E=Ka4h0YdKn=q... Link: https://lore.kernel.org/r/20220823072717.1706-2-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> Reviewed-by: Zheng Zengkai <zhengzengkai@huawei.com> --- sound/core/seq/seq_clientmgr.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c index cc93157fa950..0363670a56e7 100644 --- a/sound/core/seq/seq_clientmgr.c +++ b/sound/core/seq/seq_clientmgr.c @@ -121,13 +121,13 @@ struct snd_seq_client *snd_seq_client_use_ptr(int clientid) spin_unlock_irqrestore(&clients_lock, flags); #ifdef CONFIG_MODULES if (!in_interrupt()) { - static char client_requested[SNDRV_SEQ_GLOBAL_CLIENTS]; - static char card_requested[SNDRV_CARDS]; + static DECLARE_BITMAP(client_requested, SNDRV_SEQ_GLOBAL_CLIENTS); + static DECLARE_BITMAP(card_requested, SNDRV_CARDS); + if (clientid < SNDRV_SEQ_GLOBAL_CLIENTS) { int idx; - if (!client_requested[clientid]) { - client_requested[clientid] = 1; + if (!test_and_set_bit(clientid, client_requested)) { for (idx = 0; idx < 15; idx++) { if (seq_client_load[idx] < 0) break; @@ -142,10 +142,8 @@ struct snd_seq_client *snd_seq_client_use_ptr(int clientid) int card = (clientid - SNDRV_SEQ_GLOBAL_CLIENTS) / SNDRV_SEQ_CLIENTS_PER_CARD; if (card < snd_ecards_limit) { - if (! card_requested[card]) { - card_requested[card] = 1; + if (!test_and_set_bit(card, card_requested)) snd_request_card(card); - } snd_seq_device_load_drivers(); } } -- 2.25.1