As you may be currently aware alsa-lib (libasound) does not work very well when using
it under a kernel that has the Pax (http://pax.grsecurity.net) or Grsecurity
(http://www.grsecurity.net) Patch.
The problem is because there is a function in a function (trampoline) - So gcc
generates code that conflicts with pax. Also there is a text-relocation problem.
So I helped create patch that will fix these problems so alsa will be more usable on a
Pax/Grsecurity machine (no chpax work arounds and more security). Currently this
patch is included in alsa-lib-1.0.1 in Gentoo so it is undergoing large scale testing.
For my part I have 2 machines running with Pax and this alsa-lib patch and I have had
no problems :)
The code is a work around so if you know of a better way to do it please tell me.
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diff -Nru alsa-lib-1.0.0rc2-original/src/control/hcontrol.c
alsa-lib-1.0.0rc2/src/control/hcontrol.c
--- alsa-lib-1.0.0rc2-original/src/control/hcontrol.c Mon Oct 13 08:06:46 2003
+++ alsa-lib-1.0.0rc2/src/control/hcontrol.c Sat Dec 20 13:48:32 2003
@@ -48,6 +48,7 @@
#include <string.h>
#include <fcntl.h>
#include <sys/ioctl.h>
+#include <pthread.h>
#ifndef DOC_HIDDEN
#define __USE_GNU
#endif
@@ -409,17 +410,26 @@
return 0;
}
+static snd_hctl_t *compare_hctl;
+static int hctl_compare(const void *a, const void *b) {
+ return compare_hctl->compare(*(const snd_hctl_elem_t * const *) a,
+ *(const snd_hctl_elem_t * const *) b);
+}
+
static void snd_hctl_sort(snd_hctl_t *hctl)
{
unsigned int k;
- int compar(const void *a, const void *b) {
- return hctl->compare(*(const snd_hctl_elem_t * const *) a,
- *(const snd_hctl_elem_t * const *) b);
- }
+ static pthread_mutex_t sync_lock = PTHREAD_MUTEX_INITIALIZER;
+
assert(hctl);
assert(hctl->compare);
INIT_LIST_HEAD(&hctl->elems);
- qsort(hctl->pelems, hctl->count, sizeof(*hctl->pelems), compar);
+
+ pthread_mutex_lock(&sync_lock);
+ compare_hctl = hctl;
+ qsort(hctl->pelems, hctl->count, sizeof(*hctl->pelems), hctl_compare);
+ pthread_mutex_unlock(&sync_lock);
+
for (k = 0; k < hctl->count; k++)
list_add_tail(&hctl->pelems[k]->list, &hctl->elems);
}
diff -Nru alsa-lib-1.0.0rc2-original/src/pcm/pcm_direct.c
alsa-lib-1.0.0rc2/src/pcm/pcm_direct.c
--- alsa-lib-1.0.0rc2-original/src/pcm/pcm_direct.c Fri Oct 17 09:53:06 2003
+++ alsa-lib-1.0.0rc2/src/pcm/pcm_direct.c Sat Dec 20 13:49:22 2003
@@ -98,7 +98,6 @@
int snd_pcm_direct_shm_create_or_connect(snd_pcm_direct_t *dmix)
{
- static int snd_pcm_direct_shm_discard(snd_pcm_direct_t *dmix);
struct shmid_ds buf;
int ret = 0;
