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| author | Kyle Zeng <kylebot@openai.com> | 2026-06-07 03:41:29 +0300 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2026-06-07 10:24:16 +0300 |
| commit | 705dd6dcbc0ea87351c660c1a6443f85f1001c76 (patch) | |
| tree | 4609a3420746ddff6d04ca66173a8671ef4f6ba2 | |
| parent | 98fe3988a2efe89a1a1ded213a0561e6543e94e2 (diff) | |
| download | linux-705dd6dcbc0ea87351c660c1a6443f85f1001c76.tar.xz | |
ALSA: seq: Clear variable event pointer on read
snd_seq_read() copies a queued variable-length event header to userspace
before expanding the payload. Queued variable-length events use
SNDRV_SEQ_EXT_CHAINED internally, and data.ext.ptr points at the first
extension cell.
The read side strips SNDRV_SEQ_EXT_* bits from data.ext.len before the
copy, but it leaves data.ext.ptr untouched. A userspace sequencer client
can therefore write a direct variable event to itself and read back the
extension-cell kernel address from the returned header.
Clear the temporary header pointer before copy_to_user(). The original
queued event remains unchanged and is still passed to
snd_seq_expand_var_event(), so payload expansion keeps using the
internal chain.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kyle Zeng <kylebot@openai.com>
Link: https://patch.msgid.link/20260607004129.61345-1-kylebot@openai.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
| -rw-r--r-- | sound/core/seq/seq_clientmgr.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c index 81ef461a9118..4dda8268018e 100644 --- a/sound/core/seq/seq_clientmgr.c +++ b/sound/core/seq/seq_clientmgr.c @@ -441,6 +441,7 @@ static ssize_t snd_seq_read(struct file *file, char __user *buf, size_t count, memcpy(&tmpev, &cell->event, aligned_size); tmpev.data.ext.len &= ~SNDRV_SEQ_EXT_MASK; + tmpev.data.ext.ptr = NULL; if (copy_to_user(buf, &tmpev, aligned_size)) { err = -EFAULT; break; |