* [PATCH AUTOSEL 5.15 14/15] selftest/vm: verify mmap addr in mremap_test
[not found] <20220426190216.2351413-1-sashal@kernel.org>
@ 2022-04-26 19:02 ` Sasha Levin
2022-04-26 19:02 ` [PATCH AUTOSEL 5.15 15/15] selftest/vm: verify remap destination address " Sasha Levin
1 sibling, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2022-04-26 19:02 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Sidhartha Kumar, Shuah Khan, Andrew Morton, Linus Torvalds,
Sasha Levin, shuah, linux-mm, linux-kselftest
From: Sidhartha Kumar <sidhartha.kumar@oracle.com>
[ Upstream commit 9c85a9bae267f6b5e5e374d0d023bbbe9db096d3 ]
Avoid calling mmap with requested addresses that are less than the
system's mmap_min_addr. When run as root, mmap returns EACCES when
trying to map addresses < mmap_min_addr. This is not one of the error
codes for the condition to retry the mmap in the test.
Rather than arbitrarily retrying on EACCES, don't attempt an mmap until
addr > vm.mmap_min_addr.
Add a munmap call after an alignment check as the mappings are retained
after the retry and can reach the vm.max_map_count sysctl.
Link: https://lkml.kernel.org/r/20220420215721.4868-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/vm/mremap_test.c | 41 +++++++++++++++++++++++-
1 file changed, 40 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c
index 0624d1bd71b5..2b3b4f15185f 100644
--- a/tools/testing/selftests/vm/mremap_test.c
+++ b/tools/testing/selftests/vm/mremap_test.c
@@ -6,6 +6,7 @@
#include <errno.h>
#include <stdlib.h>
+#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <time.h>
@@ -64,6 +65,35 @@ enum {
.expect_failure = should_fail \
}
+/* Returns mmap_min_addr sysctl tunable from procfs */
+static unsigned long long get_mmap_min_addr(void)
+{
+ FILE *fp;
+ int n_matched;
+ static unsigned long long addr;
+
+ if (addr)
+ return addr;
+
+ fp = fopen("/proc/sys/vm/mmap_min_addr", "r");
+ if (fp == NULL) {
+ ksft_print_msg("Failed to open /proc/sys/vm/mmap_min_addr: %s\n",
+ strerror(errno));
+ exit(KSFT_SKIP);
+ }
+
+ n_matched = fscanf(fp, "%llu", &addr);
+ if (n_matched != 1) {
+ ksft_print_msg("Failed to read /proc/sys/vm/mmap_min_addr: %s\n",
+ strerror(errno));
+ fclose(fp);
+ exit(KSFT_SKIP);
+ }
+
+ fclose(fp);
+ return addr;
+}
+
/*
* Returns the start address of the mapping on success, else returns
* NULL on failure.
@@ -72,8 +102,15 @@ static void *get_source_mapping(struct config c)
{
unsigned long long addr = 0ULL;
void *src_addr = NULL;
+ unsigned long long mmap_min_addr;
+
+ mmap_min_addr = get_mmap_min_addr();
+
retry:
addr += c.src_alignment;
+ if (addr < mmap_min_addr)
+ goto retry;
+
src_addr = mmap((void *) addr, c.region_size, PROT_READ | PROT_WRITE,
MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED,
-1, 0);
@@ -91,8 +128,10 @@ static void *get_source_mapping(struct config c)
* alignment in the tests.
*/
if (((unsigned long long) src_addr & (c.src_alignment - 1)) ||
- !((unsigned long long) src_addr & c.src_alignment))
+ !((unsigned long long) src_addr & c.src_alignment)) {
+ munmap(src_addr, c.region_size);
goto retry;
+ }
if (!src_addr)
goto error;
--
2.35.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* [PATCH AUTOSEL 5.15 15/15] selftest/vm: verify remap destination address in mremap_test
[not found] <20220426190216.2351413-1-sashal@kernel.org>
2022-04-26 19:02 ` [PATCH AUTOSEL 5.15 14/15] selftest/vm: verify mmap addr in mremap_test Sasha Levin
@ 2022-04-26 19:02 ` Sasha Levin
1 sibling, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2022-04-26 19:02 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Sidhartha Kumar, Shuah Khan, Andrew Morton, Linus Torvalds,
Sasha Levin, shuah, linux-mm, linux-kselftest
From: Sidhartha Kumar <sidhartha.kumar@oracle.com>
[ Upstream commit 18d609daa546c919fd36b62a7b510c18de4b4af8 ]
Because mremap does not have a MAP_FIXED_NOREPLACE flag, it can destroy
existing mappings. This causes a segfault when regions such as text are
remapped and the permissions are changed.
Verify the requested mremap destination address does not overlap any
existing mappings by using mmap's MAP_FIXED_NOREPLACE flag. Keep
incrementing the destination address until a valid mapping is found or
fail the current test once the max address is reached.
Link: https://lkml.kernel.org/r/20220420215721.4868-2-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/vm/mremap_test.c | 42 ++++++++++++++++++++++--
1 file changed, 39 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c
index 2b3b4f15185f..e3ce33a9954e 100644
--- a/tools/testing/selftests/vm/mremap_test.c
+++ b/tools/testing/selftests/vm/mremap_test.c
@@ -10,6 +10,7 @@
#include <string.h>
#include <sys/mman.h>
#include <time.h>
+#include <stdbool.h>
#include "../kselftest.h"
@@ -65,6 +66,30 @@ enum {
.expect_failure = should_fail \
}
+/*
+ * Returns false if the requested remap region overlaps with an
+ * existing mapping (e.g text, stack) else returns true.
+ */
+static bool is_remap_region_valid(void *addr, unsigned long long size)
+{
+ void *remap_addr = NULL;
+ bool ret = true;
+
+ /* Use MAP_FIXED_NOREPLACE flag to ensure region is not mapped */
+ remap_addr = mmap(addr, size, PROT_READ | PROT_WRITE,
+ MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED,
+ -1, 0);
+
+ if (remap_addr == MAP_FAILED) {
+ if (errno == EEXIST)
+ ret = false;
+ } else {
+ munmap(remap_addr, size);
+ }
+
+ return ret;
+}
+
/* Returns mmap_min_addr sysctl tunable from procfs */
static unsigned long long get_mmap_min_addr(void)
{
@@ -112,8 +137,8 @@ static void *get_source_mapping(struct config c)
goto retry;
src_addr = mmap((void *) addr, c.region_size, PROT_READ | PROT_WRITE,
- MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED,
- -1, 0);
+ MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED,
+ -1, 0);
if (src_addr == MAP_FAILED) {
if (errno == EPERM || errno == EEXIST)
goto retry;
@@ -180,9 +205,20 @@ static long long remap_region(struct config c, unsigned int threshold_mb,
if (!((unsigned long long) addr & c.dest_alignment))
addr = (void *) ((unsigned long long) addr | c.dest_alignment);
+ /* Don't destroy existing mappings unless expected to overlap */
+ while (!is_remap_region_valid(addr, c.region_size) && !c.overlapping) {
+ /* Check for unsigned overflow */
+ if (addr + c.dest_alignment < addr) {
+ ksft_print_msg("Couldn't find a valid region to remap to\n");
+ ret = -1;
+ goto out;
+ }
+ addr += c.dest_alignment;
+ }
+
clock_gettime(CLOCK_MONOTONIC, &t_start);
dest_addr = mremap(src_addr, c.region_size, c.region_size,
- MREMAP_MAYMOVE|MREMAP_FIXED, (char *) addr);
+ MREMAP_MAYMOVE|MREMAP_FIXED, (char *) addr);
clock_gettime(CLOCK_MONOTONIC, &t_end);
if (dest_addr == MAP_FAILED) {
--
2.35.1
^ permalink raw reply related [flat|nested] 2+ messages in thread