diff options
| author | Cássio Gabriel <cassiogabrielcontato@gmail.com> | 2026-05-22 22:09:40 -0300 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2026-05-25 09:23:10 +0200 |
| commit | 4cc54bdd54b337e77115be5b55577d1c58608eae (patch) | |
| tree | 77364e5e102b3284bc128690654977b21dbae5a7 /sound | |
| parent | a0d9e8df2ebca290c2efff70abc05426e5a476b0 (diff) | |
| download | linux-next-history-4cc54bdd54b337e77115be5b55577d1c58608eae.tar.gz | |
ALSA: pcm: oss: Fix setup list UAF on proc write error
snd_pcm_oss_proc_write() links a newly allocated setup entry into the
OSS setup list before duplicating the task name. If the task-name
allocation fails, the error path frees the already linked entry and
leaves setup_list pointing at freed memory.
A later OSS device open can then walk the stale list entry in
snd_pcm_oss_look_for_setup() and dereference freed memory.
Allocate the task name and initialize the setup entry before publishing
the entry on setup_list. Also fetch the initial proc read iterator only
after taking setup_mutex, so all setup_list traversal follows the same
list lifetime rules.
Reported-by: syzbot+8e498074a794999eb41c@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/6a1062b7.170a0220.35b2b7.0003.GAE@google.com
Closes: https://syzkaller.appspot.com/bug?extid=8e498074a794999eb41c
Fixes: 060d77b9c04a ("[ALSA] Fix / clean up PCM-OSS setup hooks")
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260522-alsa-pcm-oss-setup-uaf-v1-1-40bdcc4d17e8@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/core/oss/pcm_oss.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c index 33fd34f0d615d..746eaf93e1a57 100644 --- a/sound/core/oss/pcm_oss.c +++ b/sound/core/oss/pcm_oss.c @@ -2974,8 +2974,10 @@ static void snd_pcm_oss_proc_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer) { struct snd_pcm_str *pstr = entry->private_data; - struct snd_pcm_oss_setup *setup = pstr->oss.setup_list; + struct snd_pcm_oss_setup *setup; + guard(mutex)(&pstr->oss.setup_mutex); + setup = pstr->oss.setup_list; while (setup) { snd_iprintf(buffer, "%s %u %u%s%s%s%s%s%s\n", setup->task_name, @@ -3060,6 +3062,13 @@ static void snd_pcm_oss_proc_write(struct snd_info_entry *entry, buffer->error = -ENOMEM; return; } + template.task_name = kstrdup(task_name, GFP_KERNEL); + if (!template.task_name) { + kfree(setup); + buffer->error = -ENOMEM; + return; + } + *setup = template; if (pstr->oss.setup_list == NULL) pstr->oss.setup_list = setup; else { @@ -3067,12 +3076,7 @@ static void snd_pcm_oss_proc_write(struct snd_info_entry *entry, setup1->next; setup1 = setup1->next); setup1->next = setup; } - template.task_name = kstrdup(task_name, GFP_KERNEL); - if (! template.task_name) { - kfree(setup); - buffer->error = -ENOMEM; - return; - } + continue; } *setup = template; } |