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 <tiwai@suse.de>
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: 81fd444aa3 ("ALSA: seq: Bind UMP device")
Signed-off-by: Zhang Cen <rollkingzzc@gmail.com>
Link: https://patch.msgid.link/20260520103249.3048345-1-rollkingzzc@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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: 9244b2c307 ("[ALSA] alsa core: convert to list_for_each_entry*")
Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>
Link: https://patch.msgid.link/20260518194023.1667857-3-maoyixie.tju@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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: d2b7060777 ("ALSA: seq: Add UMP group filter")
Cc: stable@vger.kernel.org
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260506-alsa-seq-ump-group16-filter-v1-1-b75160bf6993@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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 <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260324-alsa-seq-oss-fullsize-write-return-v1-1-66d448510538@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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 <torvalds@linux-foundation.org>
This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 <kees@kernel.org>
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: 04a86185b7 ("ALSA: seq: Clean up queue locking with auto cleanup")
Fixes: 0869afc958 ("ALSA: seq: Clean up port locking with auto cleanup")
Fixes: 99e1663395 ("ALSA: seq: Use auto-cleanup for client refcounting")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20251216140634.171890-7-tiwai@suse.de
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: 80ccbe91ad ("ALSA: seq: oss/synth: Clean up with guard and auto cleanup")
Fixes: 895a46e034 ("ALSA: seq: oss/midi: Cleanup with guard and auto-cleanup")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20251216140634.171890-6-tiwai@suse.de
snd_seq_fifo_poll_wait() evaluates f->cells without locking after
poll_wait(), and KCSAN doesn't like it as it appears to be a
data-race. Although this doesn't matter much in practice as the value
is volatile, it's still better to address it for the mind piece.
Wrap it with f->lock spinlock for avoiding the potential data race.
Reported-by: syzbot+c3dbc239259940ededba@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=c3dbc239259940ededba
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Use the auto-cleanup for the refcount management of seq_oss_synth
object. The explicit call of snd_use_lock_free() is dropped by the
magic __free(seq_oss_synth) attribute.
Along with that, replace the manual mutex and spin locks with
guard().
Only code refactoring, and no behavior change.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250827080520.7544-11-tiwai@suse.de
Use the auto-cleanup for the refcount management of seq_oss_midi
object. The explicit call of snd_use_lock_free() is dropped by the
magic __free(seq_oss_midi) attribute.
Along with that, replace the manual mutex and spin locks with
guard().
Only code refactoring, and no behavior change.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250827080520.7544-10-tiwai@suse.de
Yet more cleanup, now for seq_fifo.c about its refcount calls; the
manual refcount calls (either snd_use_lock_*() or snd_seq_fifo_lock())
are replaced with guard(snd_seq_fifo).
Only code refactoring, and no behavior change.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250827080520.7544-8-tiwai@suse.de
Yet more cleanup with the auto-cleanup macro: now we replace the
queuefree() calls with the magic pointer attribute
__free(snd_seq_queue).
Only code refactoring, and no behavior change.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250827080520.7544-7-tiwai@suse.de
Like the previous change in seq_clientmgr.c, introduce a new
auto-cleanup macro for the snd_seq_port_unlock(), and apply it
appropriately.
Only code refactoring, and no behavior change.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250827080520.7544-6-tiwai@suse.de
The current code manages the refcount of client in a way like:
snd_seq_client *client;
client = clientptr(id);
....
snd_seq_client_unlock(client);
Now we introduce an auto-cleanup macro to manage the unlock
implicitly, namely, the above will be replaced like:
snd_seq_client *client __free(snd_seq_client) = NULL;
client = clientptr(id);
and we can forget the unref call.
A part of the code in snd_seq_deliver_single_event() is factored out
to a function, so that the auto-cleanups can be applied cleanly.
This also allows us to replace some left mutex lock/unlock with
guard(), and also reduce scoped_guard() to the normal guard(), too.
Only code refactoring, and no behavior change.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250827080520.7544-5-tiwai@suse.de
Use guard() for spin locks to manage the sequencer client locking.
The code about the refcounting was modified with the new
snd_seq_client_ref() and *_unref() helpers instead of the ugly goto,
too.
Only code refactoring, and no behavior change.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250827080520.7544-3-tiwai@suse.de
Zhang Cen
Maoyi Xie
Cássio Gabriel
songxiebing
Kees Cook
Linus Torvalds
Takashi Iwai
Uwe Kleine-König