[PATCH v2 08/17] ALSA: emu10k1: move patch loader assertions into low-level functions

[Oswald Buddenhagen <oswald.buddenhagen@gmx.de>]

Convert some checks in snd_emu10k1_sample_new() back into assertions (as
they were prior to da3cec35dd (ALSA: Kill snd_assert() in sound/pci/*,
2008-08-08)), and move them into the low-level memory access functions
they protect.

Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>

---

Side note: this eliminates the memory leaks in the now gone error paths.
I don't think it was actually possible to trigger these even before the
foregoing cleanups. But if it were, it would allow a user with access to
the audio device a scope-limited DoS attack on it. This would be only a
very minor security hole, given that on modern systems it would merely
enable the current seat owner to be a nuisance to their successor, by
making a reboot necessary.
---
 sound/pci/emu10k1/emu10k1_patch.c | 4 ----
 sound/pci/emu10k1/memory.c        | 6 ++++++
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/sound/pci/emu10k1/emu10k1_patch.c b/sound/pci/emu10k1/emu10k1_patch.c
index 47d69a0e44bc..55bb60d31fe4 100644
--- a/sound/pci/emu10k1/emu10k1_patch.c
+++ b/sound/pci/emu10k1/emu10k1_patch.c
@@ -65,17 +65,13 @@ snd_emu10k1_sample_new(struct snd_emux *rec, struct snd_sf_sample *sp,
 	size = BLANK_HEAD_SIZE;
 	if (! (sp->v.mode_flags & SNDRV_SFNT_SAMPLE_8BITS))
 		size *= 2;
-	if (offset + size > blocksize)
-		return -EINVAL;
 	snd_emu10k1_synth_bzero(emu, sp->block, offset, size);
 	offset += size;

 	/* copy provided samples */
 	size = sp->v.size;
 	if (! (sp->v.mode_flags & SNDRV_SFNT_SAMPLE_8BITS))
 		size *= 2;
-	if (offset + size > blocksize)
-		return -EINVAL;
 	if (snd_emu10k1_synth_copy_from_user(emu, sp->block, offset, data, size)) {
 		snd_emu10k1_synth_free(emu, sp->block);
 		sp->block = NULL;
diff --git a/sound/pci/emu10k1/memory.c b/sound/pci/emu10k1/memory.c
index 20b07117574b..fc9444404151 100644
--- a/sound/pci/emu10k1/memory.c
+++ b/sound/pci/emu10k1/memory.c
@@ -574,6 +574,9 @@ int snd_emu10k1_synth_bzero(struct snd_emu10k1 *emu, struct snd_util_memblk *blk
 	void *ptr;
 	struct snd_emu10k1_memblk *p = (struct snd_emu10k1_memblk *)blk;

+	if (snd_BUG_ON(offset + size > p->mem.size))
+		return -EFAULT;
+
 	offset += blk->offset & (PAGE_SIZE - 1);
 	end_offset = offset + size;
 	page = get_aligned_page(offset);
@@ -604,6 +607,9 @@ int snd_emu10k1_synth_copy_from_user(struct snd_emu10k1 *emu, struct snd_util_me
 	void *ptr;
 	struct snd_emu10k1_memblk *p = (struct snd_emu10k1_memblk *)blk;

+	if (snd_BUG_ON(offset + size > p->mem.size))
+		return -EFAULT;
+
 	offset += blk->offset & (PAGE_SIZE - 1);
 	end_offset = offset + size;
 	page = get_aligned_page(offset);
--
2.42.0.419.g70bf8a5751