* [PATCH v2 1/4] selftest/vm: verify mmap addr in mremap_test
@ 2022-04-20 21:57 Sidhartha Kumar
2022-04-20 21:57 ` [PATCH v2 2/4] selftest/vm: verify remap destination address " Sidhartha Kumar
` (3 more replies)
0 siblings, 4 replies; 7+ messages in thread
From: Sidhartha Kumar @ 2022-04-20 21:57 UTC (permalink / raw)
To: shuah, akpm; +Cc: Sidhartha Kumar, linux-mm, linux-kselftest, linux-kernel
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.
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
---
v2:
-change comment for description of get_mmap_min_addr()
-fix commit message formatting
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;
--
2.27.0
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2 2/4] selftest/vm: verify remap destination address in mremap_test
2022-04-20 21:57 [PATCH v2 1/4] selftest/vm: verify mmap addr in mremap_test Sidhartha Kumar
@ 2022-04-20 21:57 ` Sidhartha Kumar
2022-04-21 19:31 ` Shuah Khan
2022-04-20 21:57 ` [PATCH v2 3/4] selftest/vm: support xfail " Sidhartha Kumar
` (2 subsequent siblings)
3 siblings, 1 reply; 7+ messages in thread
From: Sidhartha Kumar @ 2022-04-20 21:57 UTC (permalink / raw)
To: shuah, akpm; +Cc: Sidhartha Kumar, linux-mm, linux-kselftest, linux-kernel
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.
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
---
v2:
-rename remap_region_valid() to is_remap_region_valid().
-change return value of is_remap_region_valid() to bool.
-take out overflow check from is_remap_region_valid() to
inside caller.
-fail just the current test on overflow rather than existing
the program
-fix alignment of mmap calls
-change "can't" to "couldn't" in error message
-increment mremap destination address by dest_alignment
rather than src_alignment
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) {
--
2.27.0
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2 3/4] selftest/vm: support xfail in mremap_test
2022-04-20 21:57 [PATCH v2 1/4] selftest/vm: verify mmap addr in mremap_test Sidhartha Kumar
2022-04-20 21:57 ` [PATCH v2 2/4] selftest/vm: verify remap destination address " Sidhartha Kumar
@ 2022-04-20 21:57 ` Sidhartha Kumar
2022-04-20 21:57 ` [PATCH v2 4/4] selftest/vm: add skip support to mremap_test Sidhartha Kumar
2022-04-21 19:31 ` [PATCH v2 1/4] selftest/vm: verify mmap addr in mremap_test Shuah Khan
3 siblings, 0 replies; 7+ messages in thread
From: Sidhartha Kumar @ 2022-04-20 21:57 UTC (permalink / raw)
To: shuah, akpm
Cc: Sidhartha Kumar, linux-mm, linux-kselftest, linux-kernel, Shuah Khan
Use ksft_test_result_xfail for the tests which are expected to fail.
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
---
v2:
-add Reviewed-by tag
-fix commit message formatting
tools/testing/selftests/vm/mremap_test.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c
index e3ce33a9954e..237b7ccfa333 100644
--- a/tools/testing/selftests/vm/mremap_test.c
+++ b/tools/testing/selftests/vm/mremap_test.c
@@ -269,7 +269,7 @@ static void run_mremap_test_case(struct test test_case, int *failures,
if (remap_time < 0) {
if (test_case.expect_failure)
- ksft_test_result_pass("%s\n\tExpected mremap failure\n",
+ ksft_test_result_xfail("%s\n\tExpected mremap failure\n",
test_case.name);
else {
ksft_test_result_fail("%s\n", test_case.name);
--
2.27.0
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2 4/4] selftest/vm: add skip support to mremap_test
2022-04-20 21:57 [PATCH v2 1/4] selftest/vm: verify mmap addr in mremap_test Sidhartha Kumar
2022-04-20 21:57 ` [PATCH v2 2/4] selftest/vm: verify remap destination address " Sidhartha Kumar
2022-04-20 21:57 ` [PATCH v2 3/4] selftest/vm: support xfail " Sidhartha Kumar
@ 2022-04-20 21:57 ` Sidhartha Kumar
2022-04-21 19:31 ` [PATCH v2 1/4] selftest/vm: verify mmap addr in mremap_test Shuah Khan
3 siblings, 0 replies; 7+ messages in thread
From: Sidhartha Kumar @ 2022-04-20 21:57 UTC (permalink / raw)
To: shuah, akpm
Cc: Sidhartha Kumar, linux-mm, linux-kselftest, linux-kernel, Shuah Khan
Allow the mremap test to be skipped due to errors such as failing to parse
the mmap_min_addr sysctl.
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
---
v2:
-add Reviewed-by tag
-fix commit message formatting
tools/testing/selftests/vm/run_vmtests.sh | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh
index 88e15fbb5027..eae98f5de2cc 100755
--- a/tools/testing/selftests/vm/run_vmtests.sh
+++ b/tools/testing/selftests/vm/run_vmtests.sh
@@ -272,11 +272,16 @@ echo "-------------------"
echo "running mremap_test"
echo "-------------------"
./mremap_test
-if [ $? -ne 0 ]; then
+ret_val=$?
+
+if [ $ret_val -eq 0 ]; then
+ echo "[PASS]"
+elif [ $ret_val -eq $ksft_skip ]; then
+ echo "[SKIP]"
+ exitcode=$ksft_skip
+else
echo "[FAIL]"
exitcode=1
-else
- echo "[PASS]"
fi
echo "-----------------"
--
2.27.0
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2 1/4] selftest/vm: verify mmap addr in mremap_test
2022-04-20 21:57 [PATCH v2 1/4] selftest/vm: verify mmap addr in mremap_test Sidhartha Kumar
` (2 preceding siblings ...)
2022-04-20 21:57 ` [PATCH v2 4/4] selftest/vm: add skip support to mremap_test Sidhartha Kumar
@ 2022-04-21 19:31 ` Shuah Khan
3 siblings, 0 replies; 7+ messages in thread
From: Shuah Khan @ 2022-04-21 19:31 UTC (permalink / raw)
To: Sidhartha Kumar, shuah, akpm
Cc: linux-mm, linux-kselftest, linux-kernel, Shuah Khan
On 4/20/22 3:57 PM, Sidhartha Kumar wrote:
> 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.
>
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
> ---
> v2:
> -change comment for description of get_mmap_min_addr()
> -fix commit message formatting
>
Thank you.
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Andrew, please let me know if you would like me to take this
through kselftest tree.
thanks,
-- Shuah
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/4] selftest/vm: verify remap destination address in mremap_test
2022-04-20 21:57 ` [PATCH v2 2/4] selftest/vm: verify remap destination address " Sidhartha Kumar
@ 2022-04-21 19:31 ` Shuah Khan
2022-04-21 20:03 ` Andrew Morton
0 siblings, 1 reply; 7+ messages in thread
From: Shuah Khan @ 2022-04-21 19:31 UTC (permalink / raw)
To: Sidhartha Kumar, shuah, akpm
Cc: linux-mm, linux-kselftest, linux-kernel, Shuah Khan
On 4/20/22 3:57 PM, Sidhartha Kumar wrote:
> 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.
>
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
> ---
> v2:
> -rename remap_region_valid() to is_remap_region_valid().
> -change return value of is_remap_region_valid() to bool.
> -take out overflow check from is_remap_region_valid() to
> inside caller.
> -fail just the current test on overflow rather than existing
> the program
> -fix alignment of mmap calls
> -change "can't" to "couldn't" in error message
> -increment mremap destination address by dest_alignment
> rather than src_alignment
>
Thank you.
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Andrew, please let me know if you would like me to take this
through kselftest tree.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/4] selftest/vm: verify remap destination address in mremap_test
2022-04-21 19:31 ` Shuah Khan
@ 2022-04-21 20:03 ` Andrew Morton
0 siblings, 0 replies; 7+ messages in thread
From: Andrew Morton @ 2022-04-21 20:03 UTC (permalink / raw)
To: Shuah Khan
Cc: Sidhartha Kumar, shuah, linux-mm, linux-kselftest, linux-kernel
On Thu, 21 Apr 2022 13:31:56 -0600 Shuah Khan <skhan@linuxfoundation.org> wrote:
> Andrew, please let me know if you would like me to take this
> through kselftest tree.
I'm easy. If it turns up in linux-next via your tree, I drop the -mm copy.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-04-21 20:03 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-04-20 21:57 [PATCH v2 1/4] selftest/vm: verify mmap addr in mremap_test Sidhartha Kumar
2022-04-20 21:57 ` [PATCH v2 2/4] selftest/vm: verify remap destination address " Sidhartha Kumar
2022-04-21 19:31 ` Shuah Khan
2022-04-21 20:03 ` Andrew Morton
2022-04-20 21:57 ` [PATCH v2 3/4] selftest/vm: support xfail " Sidhartha Kumar
2022-04-20 21:57 ` [PATCH v2 4/4] selftest/vm: add skip support to mremap_test Sidhartha Kumar
2022-04-21 19:31 ` [PATCH v2 1/4] selftest/vm: verify mmap addr in mremap_test Shuah Khan
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