Patch to fix Pax/Grsecurity Problems

["Stephen Cook" <siti_veni@lycos.com>]

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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;