testing/libmilter: set default pthread stack size to 8 MB

This patch tries to fix various crashes for applications depending on
libmilter by setting the stack size for pthreads to 8 MB. The default
stack size for musl libc is set to 80 KB whereas glibc has it set
to 8 MB. This causes problems when a large amount of memory is
allocated on the stack.

For example, opendkim allocates blocks of 64 KB multiple times, which
causes libmilter (and therefore opendkim) to crash.
Maybe a stack size of 1 MB or 2 MB would be sufficient, but as opendkim
depends on the default glibc behavior, 8 MB should be safe.

I know this patch is kind of ugly, a better solution may be to file
a request for opendkim to allocate large blocks of memory on the heap.
But as libmilter/opendkim are fairly unusable at the moment, I suggest
to apply this patch as long as these packages are in testing.

Fixes https://bugs.alpinelinux.org/issues/6360

2 files changed, 49 insertions, 1 deletions

diff --git a/testing/libmilter/APKBUILD b/testing/libmilter/APKBUILD
index 87b8adfb1c..311023a90c 100644
--- a/testing/libmilter/APKBUILD
+++ b/testing/libmilter/APKBUILD
@@ -5,7 +5,7 @@ pkgname=libmilter
 _pkgname="sendmail"
 pkgver=1.0.2
 _pkgver=8.15.2
-pkgrel=1
+pkgrel=2
 pkgdesc="Sendmail Mail Filter API"
 url="http://www.sendmail.com/sm/open_source"
 arch="all"
@@ -14,6 +14,7 @@ makedepends="$depends_dev m4 linux-headers bsd-compat-headers"
 subpackages="$pkgname-dev $pkgname-doc"
 source="ftp://ftp.sendmail.org/pub/$_pkgname/$_pkgname.$_pkgver.tar.gz
 	libmilter-sharedlib.patch
+	default-pthread-stacksize.patch
 	site.config.m4"
 builddir="$srcdir"/$_pkgname-$_pkgver
 
@@ -37,10 +38,13 @@ package() {
 
 md5sums="a824fa7dea4d3341efb6462ccd816f00  sendmail.8.15.2.tar.gz
 49558fc2c9e38f433e0dc64d76705c05  libmilter-sharedlib.patch
+cf8d0f06d44f05f45016eee8ce644949  default-pthread-stacksize.patch
 e9fc99ec22265e5e561711f64bb9a0fa  site.config.m4"
 sha256sums="24f94b5fd76705f15897a78932a5f2439a32b1a2fdc35769bb1a5f5d9b4db439  sendmail.8.15.2.tar.gz
 3a753b0881fe622814b471ee5f9037905c7cc3ed08ef74908464ab5307e59d5a  libmilter-sharedlib.patch
+42fcd47f63248a01e9de7697ada2b52fc0aaa559683cfffa8b7198a93b98aa20  default-pthread-stacksize.patch
 fb8d43d33dda08aac9762983cadb24c54d5e3130b8808dadf4d189ceea564f48  site.config.m4"
 sha512sums="04feb37316c13b66b1518596507a7da7c16cb0bf1abf10367f7fd888a428fadb093a9efa55342fa55b936c3f0cbdc63b9e2505cd99201a69a0c05b8ad65f49f9  sendmail.8.15.2.tar.gz
 31c36b57739946c1b9c7c85307fe5c53c45d7f8cbf427a0f2248db8b74871a6f5a30ef1af524915821aeca54310d28272bcd0a587cb918192214fa5c30e4a8da  libmilter-sharedlib.patch
+ccfd21b6537362e910d721c804975e89feddf8cd9218434a5c70e3f13cb5e5ea4a2a0585fda09241a8da2e697a12e59308bcef0323c5e779166c56d07424c15a  default-pthread-stacksize.patch
 b939c19a82cd56f06102a7ad9f446c788d1eff0870f35c2f7d0a904782a7524f25adbb16c57373e0f592247d9898fdd1ef4212da15239b96ddbd9ff5010c630f  site.config.m4"
diff --git a/testing/libmilter/default-pthread-stacksize.patch b/testing/libmilter/default-pthread-stacksize.patch
new file mode 100644
index 0000000000..4e3524c230
--- /dev/null
+++ b/testing/libmilter/default-pthread-stacksize.patch
@@ -0,0 +1,44 @@
+Set default pthread stack size to 8 MB
+
+This patch tries to fix various crashes for applications depending on
+libmilter by setting the stack size for pthreads to 8 MB. The default
+stack size for musl libc is set to 80 KB whereas glibc has it set
+to 8 MB. This causes problems when a large amount of memory is
+allocated on the stack.
+
+For example, opendkim allocates blocks of 64 KB multiple times, which
+causes libmilter (and therefore opendkim) to crash.
+Maybe a stack size of 1 MB or 2 MB would be sufficient, but as opendkim
+depends on the default glibc behavior, 8 MB should be safe.
+
+Fixes https://bugs.alpinelinux.org/issues/6360
+
+--- a/libmilter/libmilter.h
++++ b/libmilter/libmilter.h
+@@ -127,10 +127,10 @@
+ # define MI_SOCK_READ(s, b, l)	read(s, b, l)
+ # define MI_SOCK_READ_FAIL(x)	((x) < 0)
+ # define MI_SOCK_WRITE(s, b, l)	write(s, b, l)
+-
+-# define thread_create(ptid,wr,arg) pthread_create(ptid, NULL, wr, arg)
+ # define sthread_get_id()	pthread_self()
+
++extern int thread_create(pthread_t *ptid, void *(*wr) (void *), void *arg);
++
+ typedef pthread_mutex_t smutex_t;
+ # define smutex_init(mp)	(pthread_mutex_init(mp, NULL) == 0)
+ # define smutex_destroy(mp)	(pthread_mutex_destroy(mp) == 0)
+--- a/libmilter/main.c
++++ b/libmilter/main.c
+@@ -16,6 +16,12 @@
+ #include <fcntl.h>
+ #include <sys/stat.h>
+
++int thread_create(pthread_t *ptid, void *(*wr) (void *), void *arg) {
++	pthread_attr_t attr;
++	pthread_attr_init(&attr);
++	pthread_attr_setstacksize(&attr,8*1024*1024);
++	return pthread_create(ptid, &attr, wr, arg);
++}
+
+ static smfiDesc_ptr smfi = NULL;