5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cássio Gabriel [ Upstream commit 611f538253d970f4d152003841544e875828d015 ] snd_seq_oss_read() checks whether the next queued OSS sequencer event fits in the remaining userspace buffer before removing it from the read queue. The check is inverted. It currently stops when the event is smaller than the remaining buffer, so a normal 4-byte event is not copied for an 8-byte read buffer. Conversely, an 8-byte event can be copied for a smaller read count. Break only when the remaining userspace buffer is smaller than the next event, and report -EINVAL if no complete event has been copied. This prevents an undersized read from looking like end-of-file while leaving the event queued for a later read with a large enough buffer. Signed-off-by: Cássio Gabriel Link: https://patch.msgid.link/20260602-alsa-seq-oss-read-size-check-v1-1-10e59b1742e0@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin --- sound/core/seq/oss/seq_oss_rw.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/sound/core/seq/oss/seq_oss_rw.c b/sound/core/seq/oss/seq_oss_rw.c index 307ef98c44c7b..45bb458597708 100644 --- a/sound/core/seq/oss/seq_oss_rw.c +++ b/sound/core/seq/oss/seq_oss_rw.c @@ -57,7 +57,8 @@ snd_seq_oss_read(struct seq_oss_devinfo *dp, char __user *buf, int count) break; } ev_len = ev_length(&rec); - if (ev_len < count) { + if (count < ev_len) { + err = -EINVAL; snd_seq_oss_readq_unlock(readq, flags); break; } -- 2.53.0