kernel/linux.git/sound/core/timer.c, branch v7.1-rc5

ALSA: timer: avoid past-the-end iterator in snd_timer_dev_register()

2026-05-19T05:38:54+00:00

snd_timer_dev_register() walks snd_timer_list looking for the ordered insertion point and on loop fall-through passes &timer1->device_list to list_add_tail(): list_for_each_entry(timer1, &snd_timer_list, device_list) { ... break; /* on found-position */ ... } list_add_tail(&timer->device_list, &timer1->device_list); When the loop walks all entries without break, timer1 is past-the-end. &timer1->device_list aliases &snd_timer_list (the list head) via container_of offset cancellation, so the insert lands at the list tail. That is the intended behaviour, but the access is undefined per C11 even though it works in practice. Track an explicit insert_before pointer initialised to the list head and overwritten to &timer1->device_list only when the loop breaks early. The observable behaviour is unchanged. Fixes: 9244b2c3079f ("[ALSA] alsa core: convert to list_for_each_entry*") Signed-off-by: Maoyi Xie Link: https://patch.msgid.link/20260518194023.1667857-2-maoyixie.tju@gmail.com Signed-off-by: Takashi Iwai

ALSA: timer: keep a list of open masters for slave lookup

2026-03-17T08:16:24+00:00

snd_timer_check_slave() still walks all registered timers and all open timer instances to find a matching master for a newly opened slave. Maintain a global list of open master instances that can accept slave links and use it for the slave lookup path instead. This keeps the existing matching semantics while avoiding the nested walk over snd_timer_list and each timer open_list_head. The reverse path in snd_timer_check_master() already scans only the pending slave list, so this makes both lookup paths closer in shape without changing the master/slave linking logic. Signed-off-by: Cássio Gabriel Link: https://patch.msgid.link/20260316-alsa-timer-master-list-v1-1-fb95e547110a@gmail.com Signed-off-by: Takashi Iwai

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

ALSA: timer: Relax __free() variable declarations

2025-12-17T09:08:30+00:00

We used to have a variable declaration with __free() initialized with NULL. This was to keep the old coding style rule, but recently it's relaxed and rather recommends to follow the new rule to declare in place of use for __free() -- which avoids potential deadlocks or UAFs with nested cleanups. Although the current code has no bug, per se, let's follow the new standard and move the declaration to the place of assignment (or directly assign the allocated result) instead of NULL initializations. Fixes: ed96f6394e1b ("ALSA: timer: Use automatic cleanup of kfree()") Fixes: 37745918e0e7 ("ALSA: timer: Introduce virtual userspace-driven timers") Signed-off-by: Takashi Iwai Link: https://patch.msgid.link/20251216140634.171890-8-tiwai@suse.de

ALSA: timer: fix ida_free call while not allocated

2025-08-21T07:12:24+00:00

In the snd_utimer_create() function, if the kasprintf() function return NULL, snd_utimer_put_id() will be called, finally use ida_free() to free the unallocated id 0. the syzkaller reported the following information: ------------[ cut here ]------------ ida_free called for id=0 which is not allocated. WARNING: CPU: 1 PID: 1286 at lib/idr.c:592 ida_free+0x1fd/0x2f0 lib/idr.c:592 Modules linked in: CPU: 1 UID: 0 PID: 1286 Comm: syz-executor164 Not tainted 6.15.8 #3 PREEMPT(lazy) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-4.fc42 04/01/2014 RIP: 0010:ida_free+0x1fd/0x2f0 lib/idr.c:592 Code: f8 fc 41 83 fc 3e 76 69 e8 70 b2 f8 (...) RSP: 0018:ffffc900007f79c8 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 1ffff920000fef3b RCX: ffffffff872176a5 RDX: ffff88800369d200 RSI: 0000000000000000 RDI: ffff88800369d200 RBP: 0000000000000000 R08: ffffffff87ba60a5 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f6f1abc1740(0000) GS:ffff8880d76a0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6f1ad7a784 CR3: 000000007a6e2000 CR4: 00000000000006f0 Call Trace: snd_utimer_put_id sound/core/timer.c:2043 [inline] [snd_timer] snd_utimer_create+0x59b/0x6a0 sound/core/timer.c:2184 [snd_timer] snd_utimer_ioctl_create sound/core/timer.c:2202 [inline] [snd_timer] __snd_timer_user_ioctl.isra.0+0x724/0x1340 sound/core/timer.c:2287 [snd_timer] snd_timer_user_ioctl+0x75/0xc0 sound/core/timer.c:2298 [snd_timer] vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __x64_sys_ioctl+0x198/0x200 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x7b/0x160 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x76/0x7e [...] The utimer->id should be set properly before the kasprintf() function, ensures the snd_utimer_put_id() function will free the allocated id. Fixes: 37745918e0e75 ("ALSA: timer: Introduce virtual userspace-driven timers") Signed-off-by: Dewei Meng Link: https://patch.msgid.link/20250821014317.40786-1-mengdewei@cqsoftware.com.cn Signed-off-by: Takashi Iwai

ALSA: timer: Replace deprecated strcpy() with strscpy()

2025-06-30T12:07:42+00:00

strcpy() is deprecated; use strscpy() instead. No functional changes intended. Link: https://github.com/KSPP/linux/issues/88 Signed-off-by: Thorsten Blum Link: https://patch.msgid.link/20250630105420.1448-2-thorsten.blum@linux.dev Signed-off-by: Takashi Iwai

treewide, timers: Rename from_timer() to timer_container_of()

2025-06-08T07:07:37+00:00

Move this API to the canonical timer_*() namespace. [ tglx: Redone against pre rc1 ] Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com

treewide: Switch/rename to timer_delete[_sync]()

2025-04-05T08:30:12+00:00

timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree over and remove the historical wrapper inlines. Conversion was done with coccinelle plus manual fixups where necessary. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar

ALSA: timer: Don't take register_mutex with copy_from/to_user()

2025-03-21T17:28:28+00:00

The infamous mmap_lock taken in copy_from/to_user() can be often problematic when it's called inside another mutex, as they might lead to deadlocks. In the case of ALSA timer code, the bad pattern is with guard(mutex)(®ister_mutex) that covers copy_from/to_user() -- which was mistakenly introduced at converting to guard(), and it had been carefully worked around in the past. This patch fixes those pieces simply by moving copy_from/to_user() out of the register mutex lock again. Fixes: 3923de04c817 ("ALSA: pcm: oss: Use guard() for setup") Reported-by: syzbot+2b96f44164236dda0f3b@syzkaller.appspotmail.com Closes: https://lore.kernel.org/67dd86c8.050a0220.25ae54.0059.GAE@google.com Link: https://patch.msgid.link/20250321172653.14310-1-tiwai@suse.de Signed-off-by: Takashi Iwai