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

ALSA: seq: Serialize UMP output teardown with event_input

2026-05-20T11:10:40+00:00

seq_ump_process_event() borrows client->out_rfile.output without synchronizing with the first-open and last-close transition in seq_ump_client_open() and seq_ump_client_close(). The last output unuse can therefore drop opened[STR_OUT] to zero and release the rawmidi file while an in-flight event_input callback is still inside snd_rawmidi_kernel_write(). That leaves the rawmidi substream runtime exposed to teardown before the write path has taken its own buffer reference. Add a per-client rwlock for the event_input-visible output file. Publish a newly opened output file under the write side, and hold the read side from the output lookup through snd_rawmidi_kernel_write(). The last output close copies and clears the visible output file under the write side, then drops the lock and releases the saved rawmidi file. Use IRQ-safe rwlock guards because event_input can also be reached from atomic sequencer delivery. The buggy scenario involves two paths, with each column showing the order within that path: path A label: event_input path path B label: last unuse path 1. seq_ump_process_event() reads 1. seq_ump_client_close() client->out_rfile.output. drops opened[STR_OUT] to zero. 2. snd_rawmidi_kernel_write1() 2. snd_rawmidi_kernel_release() has not yet pinned runtime. closes the output file. 3. The writer continues using 3. close_substream() frees the borrowed substream. substream->runtime. This keeps the output substream and runtime alive for the full event_input write while keeping rawmidi release outside the rwlock. KASAN reproduced this as a slab-use-after-free in snd_rawmidi_kernel_write1(), with allocation through seq_ump_use()/snd_seq_port_connect() and free through seq_ump_unuse()/snd_seq_port_disconnect(). Suggested-by: Takashi Iwai Validation reproduced this kernel report: KASAN slab-use-after-free in snd_rawmidi_kernel_write1+0x9d/0x400 RIP: 0033:0x7f5528af837f Read of size 8 Call trace: dump_stack_lvl+0x73/0xb0 (?:?) print_report+0xd1/0x650 (?:?) srso_alias_return_thunk+0x5/0xfbef5 (?:?) __virt_addr_valid+0x1a7/0x340 (?:?) kasan_complete_mode_report_info+0x64/0x200 (?:?) kasan_report+0xf7/0x130 (?:?) snd_rawmidi_kernel_write1+0x9d/0x400 (?:?) __asan_load8+0x82/0xb0 (?:?) update_stack_state+0x1ef/0x2d0 (?:?) snd_rawmidi_kernel_write+0x1a/0x20 (?:?) seq_ump_process_event+0xd4/0x120 (sound/core/seq/seq_ump_client.c:82) __snd_seq_deliver_single_event+0x8a/0xe0 (?:?) snd_seq_deliver_from_ump+0x2b2/0xd60 (?:?) lock_acquire+0x14e/0x2e0 (?:?) find_held_lock+0x31/0x90 (?:?) snd_seq_port_use_ptr+0xa6/0xe0 (?:?) __kasan_check_write+0x18/0x20 (?:?) do_raw_read_unlock+0x32/0xa0 (?:?) _raw_read_unlock+0x26/0x50 (?:?) snd_seq_deliver_single_event+0x45c/0x4b0 (?:?) snd_seq_deliver_event+0x10d/0x1b0 (?:?) snd_seq_client_enqueue_event+0x192/0x240 (?:?) snd_seq_write+0x2cd/0x450 (?:?) apparmor_file_permission+0x20/0x30 (?:?) security_file_permission+0x51/0x60 (?:?) vfs_write+0x1ce/0x850 (?:?) __fget_files+0x12b/0x220 (?:?) lock_release+0xc8/0x2a0 (?:?) __rcu_read_unlock+0x74/0x2d0 (?:?) __fget_files+0x135/0x220 (?:?) ksys_write+0x15a/0x180 (?:?) rcu_is_watching+0x24/0x60 (?:?) __x64_sys_write+0x46/0x60 (?:?) x64_sys_call+0x7d/0x20d0 (?:?) do_syscall_64+0xc1/0x360 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?) Fixes: 81fd444aa371 ("ALSA: seq: Bind UMP device") Signed-off-by: Zhang Cen Link: https://patch.msgid.link/20260520103249.3048345-1-rollkingzzc@gmail.com Signed-off-by: Takashi Iwai

ALSA: seq: avoid past-the-end iterator in snd_seq_create_port()

2026-05-19T05:39:06+00:00

snd_seq_create_port() walks client->ports_list_head looking for the ordered insertion point and on loop fall-through passes &p->list to list_add_tail(): list_for_each_entry(p, &client->ports_list_head, list) { if (p->addr.port == port) { kfree(new_port); return -EBUSY; } if (p->addr.port > num) break; ... } list_add_tail(&new_port->list, &p->list); When the loop walks all entries without break (e.g., the new port sorts last), p is past-the-end. &p->list aliases &client->ports_list_head (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 &p->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/20260518194023.1667857-3-maoyixie.tju@gmail.com Signed-off-by: Takashi Iwai

ALSA: seq: Fix UMP group 16 filtering

2026-05-06T07:56:54+00:00

The sequencer UAPI defines group_filter as an unsigned int bitmap. Bit 0 filters groupless messages and bits 1-16 filter UMP groups 1-16. The internal snd_seq_client storage is only unsigned short, so bit 16 is truncated when userspace sets the filter. The same truncation affects the automatic UMP client filter used to avoid delivery to inactive groups, so events for group 16 cannot be filtered. Store the internal bitmap as unsigned int and keep both userspace-provided and automatically generated values limited to the defined UAPI bits. Fixes: d2b706077792 ("ALSA: seq: Add UMP group filter") Cc: stable@vger.kernel.org Signed-off-by: Cássio Gabriel Link: https://patch.msgid.link/20260506-alsa-seq-ump-group16-filter-v1-1-b75160bf6993@gmail.com Signed-off-by: Takashi Iwai

ALSA: seq_oss: return full count for successful SEQ_FULLSIZE writes

2026-03-27T13:40:24+00:00

snd_seq_oss_write() currently returns the raw load_patch() callback result for SEQ_FULLSIZE events. That callback is documented as returning 0 on success and -errno on failure, but snd_seq_oss_write() is the file write path and should report the number of user bytes consumed on success. Some in-tree backends also return backend-specific positive values, which can still be shorter than the original write size. Return the full byte count for successful SEQ_FULLSIZE writes. Preserve negative errors and convert any nonnegative completion to the original count. Cc: stable@vger.kernel.org Signed-off-by: Cássio Gabriel Link: https://patch.msgid.link/20260324-alsa-seq-oss-fullsize-write-return-v1-1-66d448510538@gmail.com Signed-off-by: Takashi Iwai

ALSA: core/seq: Optimize the return logic in cc_ev_to_ump_midi2

2026-03-27T13:40:24+00:00

There are multiple early return branches within the func, and compiler optimizations(such as -O2/-O3)lead to abnormal stack frame analysis - objtool cannot comfirm that the stack frames of all branches can be correctly restored, thus generating false warnings. Below: >> sound/core/seq/seq_ump_convert.o: warning: objtool: cc_ev_to_ump_midi2+0x589: return with modified stack frame So we modify it by uniformly returning at the and of the function. Signed-off-by: songxiebing Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202503200535.J3hAvcjw-lkp@intel.com/ Link: https://patch.msgid.link/20260325015119.175835-1-songxiebing@kylinos.cn Signed-off-by: Takashi Iwai

Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses

2026-02-22T16:26:33+00:00

Conversion performed via this Coccinelle script: // SPDX-License-Identifier: GPL-2.0-only // Options: --include-headers-for-types --all-includes --include-headers --keep-comments virtual patch @gfp depends on patch && !(file in "tools") && !(file in "samples")@ identifier ALLOC = {kmalloc_obj,kmalloc_objs,kmalloc_flex, kzalloc_obj,kzalloc_objs,kzalloc_flex, kvmalloc_obj,kvmalloc_objs,kvmalloc_flex, kvzalloc_obj,kvzalloc_objs,kvzalloc_flex}; @@ ALLOC(... - , GFP_KERNEL ) $ make coccicheck MODE=patch COCCI=gfp.cocci Build and boot tested x86_64 with Fedora 42's GCC and Clang: Linux version 6.19.0+ (user@host) (gcc (GCC) 15.2.1 20260123 (Red Hat 15.2.1-7), GNU ld version 2.44-12.fc42) #1 SMP PREEMPT_DYNAMIC 1970-01-01 Linux version 6.19.0+ (user@host) (clang version 20.1.8 (Fedora 20.1.8-4.fc42), LLD 20.1.8) #1 SMP PREEMPT_DYNAMIC 1970-01-01 Signed-off-by: Kees Cook Signed-off-by: Linus Torvalds

Convert more 'alloc_obj' cases to default GFP_KERNEL arguments

2026-02-22T04:03:00+00:00

This converts some of the visually simpler cases that have been split over multiple lines. I only did the ones that are easy to verify the resulting diff by having just that final GFP_KERNEL argument on the next line. Somebody should probably do a proper coccinelle script for this, but for me the trivial script actually resulted in an assertion failure in the middle of the script. I probably had made it a bit _too_ trivial. So after fighting that far a while I decided to just do some of the syntactically simpler cases with variations of the previous 'sed' scripts. The more syntactically complex multi-line cases would mostly really want whitespace cleanup anyway. Signed-off-by: Linus Torvalds

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: seq: 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. Note that there is a remaining __free() with NULL initialization; it's because of the non-trivial code conditionally assigning the data. Fixes: 04a86185b785 ("ALSA: seq: Clean up queue locking with auto cleanup") Fixes: 0869afc958a0 ("ALSA: seq: Clean up port locking with auto cleanup") Fixes: 99e16633958b ("ALSA: seq: Use auto-cleanup for client refcounting") Signed-off-by: Takashi Iwai Link: https://patch.msgid.link/20251216140634.171890-7-tiwai@suse.de