Changeset: 60ac438a9b58 for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=60ac438a9b58
Modified Files:
sql/backends/monet5/UDF/capi/Tests/capi03.sql
sql/backends/monet5/UDF/capi/capi.c
Branch: jitudf
Log Message:
Use pthread_sigmask to stop blocking SIGSEGV/SIGBUS in C UDFs.
We want to catch these signals so we can detect and prevent writing to input
BATs using mprotect.
diffs (208 lines):
diff --git a/sql/backends/monet5/UDF/capi/Tests/capi03.sql
b/sql/backends/monet5/UDF/capi/Tests/capi03.sql
--- a/sql/backends/monet5/UDF/capi/Tests/capi03.sql
+++ b/sql/backends/monet5/UDF/capi/Tests/capi03.sql
@@ -50,20 +50,35 @@ SELECT capi03(i) FROM integers;
ROLLBACK;
--- START TRANSACTION;
+START TRANSACTION;
--- # Modify input data
--- CREATE FUNCTION capi03(inp INTEGER) RETURNS INTEGER LANGUAGE C {
--- inp.data[0] = 10;
--- result->initialize(result, inp.count);
--- for(size_t i = 0; i < inp.count; i++) {
--- result->data[i] = inp.data[i] * 2;
--- }
--- };
+# Modify input data
+CREATE FUNCTION capi03(inp INTEGER) RETURNS INTEGER LANGUAGE C {
+ inp.data[0] = 10;
+ result->initialize(result, inp.count);
+ for(size_t i = 0; i < inp.count; i++) {
+ result->data[i] = inp.data[i] * 2;
+ }
+};
--- CREATE TABLE integers(i INTEGER);
--- INSERT INTO integers VALUES (1), (2), (3), (4), (5);
+CREATE TABLE integers(i INTEGER);
+INSERT INTO integers VALUES (1), (2), (3), (4), (5);
--- SELECT capi03(i) FROM integers;
+SELECT capi03(i) FROM integers;
--- ROLLBACK;
+ROLLBACK;
+
+START TRANSACTION;
+
+# Trigger a segfault
+CREATE FUNCTION capi03(inp INTEGER) RETURNS INTEGER LANGUAGE C {
+ int x = *((int*)NULL);
+};
+
+CREATE TABLE integers(i INTEGER);
+INSERT INTO integers VALUES (1), (2), (3), (4), (5);
+
+SELECT capi03(i) FROM integers;
+
+ROLLBACK;
+
diff --git a/sql/backends/monet5/UDF/capi/capi.c
b/sql/backends/monet5/UDF/capi/capi.c
--- a/sql/backends/monet5/UDF/capi/capi.c
+++ b/sql/backends/monet5/UDF/capi/capi.c
@@ -12,7 +12,15 @@
#include "mtime.h"
-#include "setjmp.h"
+#include <setjmp.h>
+#include <signal.h>
+#include <stdio.h>
+#include <malloc.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <string.h>
static __thread jmp_buf jump_buffer;
@@ -49,6 +57,7 @@ static void handler(int sig, siginfo_t *
(void) sig;
(void) si;
(void) unused;
+ // we caught a segfault or bus error
longjmp(jump_buffer, 1);
}
@@ -61,24 +70,22 @@ typedef struct _mprotected_region {
static char*
mprotect_region(void* addr, size_t len, int flags, mprotected_region**
regions) {
-#ifdef __APPLE__
- // we don't mprotect on OSX for now
- return NULL;
-#else
mprotected_region* region;
+ int pagesize;
+ void* page_begin;
if (len == 0) return NULL;
// check if the region is page-aligned
- /*
- int pagesize = getpagesize();
- void* page_begin = (void*)((size_t)addr - (size_t)addr % pagesize);
+
+ pagesize = getpagesize();
+ page_begin = (void*)((size_t)addr - (size_t)addr % pagesize);
if (page_begin != addr) {
// data is not page-aligned
- len += (addr - page_begin);
+ len += ((size_t)addr - (size_t)page_begin);
addr = page_begin;
}
// page align len
len = len % pagesize == 0 ? len : len - len % pagesize + pagesize;
-*/
+
region = GDKmalloc(sizeof(mprotected_region));
if (!region) {
return MAL_MALLOC_FAIL;
@@ -92,7 +99,6 @@ mprotect_region(void* addr, size_t len,
region->next = *regions;
*regions = region;
return NULL;
-#endif
}
static char*
@@ -202,7 +208,7 @@ GENERATE_BASE_HEADERS(cudf_data_timestam
const char *debug_flag = "capi_use_debug";
const char *cc_flag = "capi_cc";
-#define JIT_COMPILER_NAME "clang"
+#define JIT_COMPILER_NAME "cc"
static size_t GetTypeCount(int type, void* struct_ptr);
static void* GetTypeData(int type, void* struct_ptr);
@@ -252,7 +258,8 @@ CUDFeval(Client cntxt, MalBlkPtr mb, Mal
lng initial_output_count = -1;
- struct sigaction sa;
+ struct sigaction sa, oldsa, oldsb;
+ sigset_t signal_set;
#ifdef NDEBUG
int debug_build = GDKgetenv_istrue(debug_flag) ||
GDKgetenv_isyes(debug_flag);
@@ -267,6 +274,16 @@ CUDFeval(Client cntxt, MalBlkPtr mb, Mal
(void) cntxt;
+ // we need to be able to catch segfaults and bus errors
+ // so we can work with mprotect to prevent UDFs from changing
+ // the input data
+
+ // we remove them from the pthread_sigmask
+ (void) sigemptyset(&signal_set);
+ (void) sigaddset(&signal_set, SIGSEGV);
+ (void) sigaddset(&signal_set, SIGBUS);
+ (void) pthread_sigmask(SIG_UNBLOCK, &signal_set, NULL);
+
memset(&sa, 0, sizeof(sa));
if (!grouped) {
@@ -687,7 +704,7 @@ CUDFeval(Client cntxt, MalBlkPtr mb, Mal
goto wrapup;
} else if (ret > 0) {
if (ret == 1) {
- msg = createException(MAL, "cudf.eval", "Attempting to
write to read-only memory");
+ msg = createException(MAL, "cudf.eval", "Attempting to
write to the input or triggered a segfault/bus error");
goto wrapup;
} else if (ret == 2) {
msg = createException(MAL, "cudf.eval", "Malloc failure
in internal function!");
@@ -700,10 +717,11 @@ CUDFeval(Client cntxt, MalBlkPtr mb, Mal
}
// set up the signal handler for catching segfaults
+ memset(&sa, 0, sizeof(sa));
sa.sa_flags = SA_SIGINFO;
- sigemptyset(&sa.sa_mask);
+ sigfillset(&sa.sa_mask);
sa.sa_sigaction = handler;
- if (sigaction(SIGSEGV, &sa, NULL) < 0 || sigaction(SIGBUS, &sa, NULL) <
0) {
+ if (sigaction(SIGSEGV, &sa, &oldsa) == -1 || sigaction(SIGBUS, &sa,
&oldsb) == -1) {
msg = createException(MAL, "cudf.eval", "Failed to set signal
handler: %s", strerror(errno));
errno = 0;
goto wrapup;
@@ -714,7 +732,7 @@ CUDFeval(Client cntxt, MalBlkPtr mb, Mal
msg = func(inputs, outputs, wrapped_GDK_malloc);
// clear the signal handlers
- if (sigaction(SIGSEGV, NULL, NULL) < 0 || sigaction(SIGBUS, NULL, NULL)
< 0) {
+ if (sigaction(SIGSEGV, &oldsa, NULL) == -1 || sigaction(SIGBUS, &oldsb,
NULL) == -1) {
msg = createException(MAL, "cudf.eval", "Failed to unset signal
handler: %s", strerror(errno));
errno = 0;
goto wrapup;
@@ -824,8 +842,8 @@ wrapup:
// cleanup
// remove the signal handler, if any was set
if (sa.sa_sigaction) {
- sigaction(SIGBUS, NULL, NULL);
- sigaction(SIGSEGV, NULL, NULL);
+ sigaction(SIGSEGV, &oldsa, NULL);
+ sigaction(SIGBUS, &oldsb, NULL);
memset(&sa, 0, sizeof (sa));
}
@@ -836,6 +854,8 @@ wrapup:
GDKfree(regions);
regions = next;
}
+ // block segfaults and bus errors again after we exit
+ (void) pthread_sigmask(SIG_BLOCK, &signal_set, NULL);
// argument names (input)
if (args) {
for(i = 0; i < (size_t) pci->argc; i++) {
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