[LTP] [PATCH v3] shmctl03: Fix 32-bit compat mode failure by adjusting comparisons for compat mode truncation

[Wei Gao via ltp <ltp@lists.linux.it>]

On 64-bit kernels, the default shmmax and shmall values often exceed
the range of a 32-bit unsigned long or are clipped differently by the
kernel's compat syscall layer than they appear in /proc.

Link: https://lore.kernel.org/ltp/aJm5SBOaRoe1e0PB@yuki.lan/
Signed-off-by: Wei Gao <wegao@suse.com>
Suggested-by: Cyril Hrubis <chrubis@suse.cz>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 include/tst_assert.h                          |  9 +++++---
 lib/tst_assert.c                              | 22 ++++++++++++++-----
 .../kernel/syscalls/ipc/shmctl/shmctl03.c     | 17 +++++++++++---
 3 files changed, 37 insertions(+), 11 deletions(-)

diff --git a/include/tst_assert.h b/include/tst_assert.h
index dcb62dfea..8b2c8f655 100644
--- a/include/tst_assert.h
+++ b/include/tst_assert.h
@@ -21,14 +21,17 @@ void tst_assert_int(const char *file, const int lineno,
 #define TST_ASSERT_FILE_INT(path, prefix, val) \
 	tst_assert_file_int(__FILE__, __LINE__, path, prefix, val)
 
+#define TST_ASSERT_SATURATED_INT   0x01
+#define TST_ASSERT_BITWISE         0x04
+
 /*
  * Same as tst_assert_int() but for unsigned long.
  */
 void tst_assert_ulong(const char *file, const int lineno,
-                      const char *path, unsigned long val);
+                      const char *path, unsigned long val, int flags);
 
-#define TST_ASSERT_ULONG(path, val) \
-	tst_assert_ulong(__FILE__, __LINE__, path, val)
+#define TST_ASSERT_ULONG(path, val, ...) \
+	tst_assert_ulong(__FILE__, __LINE__, path, val, (0, ##__VA_ARGS__))
 
 /*
  * Asserts that integer value stored in the prefix field of file pointed by path
diff --git a/lib/tst_assert.c b/lib/tst_assert.c
index b68bd5d39..773a10e49 100644
--- a/lib/tst_assert.c
+++ b/lib/tst_assert.c
@@ -5,6 +5,7 @@
  * Copyright (c) 2020 Cyril Hrubis <chrubis@suse.cz>
  */
 #include <stdio.h>
+#include <limits.h>
 #define TST_NO_DEFAULT_MAIN
 #include "tst_assert.h"
 #include "tst_test.h"
@@ -23,18 +24,29 @@ void tst_assert_int(const char *file, const int lineno, const char *path, int va
 	tst_res_(file, lineno, TFAIL, "%s != %d got %d", path, val, sys_val);
 }
 
-void tst_assert_ulong(const char *file, const int lineno, const char *path, unsigned long val)
+void tst_assert_ulong(const char *file, const int lineno, const char *path,
+		      unsigned long val, int flags)
 {
-	unsigned long sys_val;
+	unsigned long long sys_val_64;
+	unsigned long expected_val;
 
-	safe_file_scanf(file, lineno, NULL, path, "%lu", &sys_val);
+	safe_file_scanf(file, lineno, NULL, path, "%llu", &sys_val_64);
 
-	if (val == sys_val) {
+	if (flags & TST_ASSERT_SATURATED_INT) {
+		expected_val = (sys_val_64 > (unsigned long long)INT_MAX) ? (unsigned long)INT_MAX : (unsigned long)sys_val_64;
+	} else if (flags & TST_ASSERT_BITWISE) {
+		expected_val = (unsigned long)(sys_val_64 & 0xFFFFFFFFULL);
+	} else {
+		expected_val = (unsigned long)sys_val_64;
+	}
+
+	if (val == expected_val) {
 		tst_res_(file, lineno, TPASS, "%s = %lu", path, val);
 		return;
 	}
 
-	tst_res_(file, lineno, TFAIL, "%s != %lu got %lu", path, val, sys_val);
+	tst_res_(file, lineno, TFAIL, "%s != %lu got %lu (raw: %llu)",
+		path, val, expected_val, sys_val_64);
 }
 
 void tst_assert_file_int(const char *file, const int lineno, const char *path, const char *prefix, int val)
diff --git a/testcases/kernel/syscalls/ipc/shmctl/shmctl03.c b/testcases/kernel/syscalls/ipc/shmctl/shmctl03.c
index a1f53e7c1..e6c7a8027 100644
--- a/testcases/kernel/syscalls/ipc/shmctl/shmctl03.c
+++ b/testcases/kernel/syscalls/ipc/shmctl/shmctl03.c
@@ -30,9 +30,20 @@ static void verify_ipcinfo(void)
 	else
 		tst_res(TPASS, "shmmin = 1");
 
-	TST_ASSERT_ULONG("/proc/sys/kernel/shmmax", info.shmmax);
-	TST_ASSERT_ULONG("/proc/sys/kernel/shmmni", info.shmmni);
-	TST_ASSERT_ULONG("/proc/sys/kernel/shmall", info.shmall);
+	if (tst_is_compat_mode()) {
+		/*
+		 * On 64-bit kernel, shmmax is clamped to INT_MAX for 32-bit
+		 * compat syscall, while shmmni and shmall are truncated
+		 * to 32-bit.
+		 */
+		TST_ASSERT_ULONG("/proc/sys/kernel/shmmax", info.shmmax, TST_ASSERT_SATURATED_INT);
+		TST_ASSERT_ULONG("/proc/sys/kernel/shmmni", info.shmmni, TST_ASSERT_BITWISE);
+		TST_ASSERT_ULONG("/proc/sys/kernel/shmall", info.shmall, TST_ASSERT_BITWISE);
+	} else {
+		TST_ASSERT_ULONG("/proc/sys/kernel/shmmax", info.shmmax);
+		TST_ASSERT_ULONG("/proc/sys/kernel/shmmni", info.shmmni);
+		TST_ASSERT_ULONG("/proc/sys/kernel/shmall", info.shmall);
+	}
 }
 
 static struct tst_test test = {
-- 
2.52.0


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