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ALSA: seq: Use flexible array for device arguments

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snd_seq_device_new() allocates struct snd_seq_device together with a
caller-specific argument area. SNDRV_SEQ_DEVICE_ARGPTR() reaches that
area by adding sizeof(struct snd_seq_device) to the object pointer.

Make the trailing storage explicit with a flexible array and allocate it
with kzalloc_flex(). This makes the object layout self-describing and
avoids open-coded size arithmetic in the allocation and accessor.

Reject negative argsize values before calculating the allocation size.
Current in-tree callers pass either zero or sizeof() values, but the
function takes an int size argument and should not let a negative value
flow into unsigned allocation arithmetic.

Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260531-alsa-seq-flex-args-v2-1-6e068d4ed9b0@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Cássio Gabriel
2026-05-31 20:41:41 -03:00
committed by Takashi Iwai
parent 635b5c6622
commit 8a2d0b5496
2 changed files with 6 additions and 2 deletions
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3
include/sound/seq_device.h
View File

@@ -22,6 +22,7 @@ struct snd_seq_device {
void *private_data; /* private data for the caller */
void (*private_free)(struct snd_seq_device *device);
struct device dev;
unsigned char args[]; /* driver-specific argument */
};
#define to_seq_dev(_dev) \
@@ -64,7 +65,7 @@ void snd_seq_device_load_drivers(void);
int snd_seq_device_new(struct snd_card *card, int device, const char *id,
int argsize, struct snd_seq_device **result);
#define SNDRV_SEQ_DEVICE_ARGPTR(dev) (void *)((char *)(dev) + sizeof(struct snd_seq_device))
#define SNDRV_SEQ_DEVICE_ARGPTR(dev) ((void *)(dev)->args)
int __must_check __snd_seq_driver_register(struct snd_seq_driver *drv,
struct module *mod);

5
sound/core/seq_device.c
View File

@@ -234,7 +234,10 @@ int snd_seq_device_new(struct snd_card *card, int device, const char *id,
if (snd_BUG_ON(!id))
return -EINVAL;
dev = kzalloc(sizeof(*dev) + argsize, GFP_KERNEL);
if (argsize < 0)
return -EINVAL;
dev = kzalloc_flex(*dev, args, argsize);
if (!dev)
return -ENOMEM;