proc_int_k2u_conv_kop() returns the sign through *negp and the magnitude
through *u_ptr. For a negative value it used to convert the
sign-extended int and negate afterwards, so the magnitude came back as a
wrapped 64-bit number. Nothing noticed, because no test wrote a
negative value to a jiffies sysctl.
Write one to each of the three int converters and require the value to
read back unchanged. Each value is chosen to convert exactly at every
CONFIG_HZ, so the test does not depend on it:
converter write jiffies stored reads back
jiffies -1 -HZ -1
ms_jiffies -1000 -HZ -1000
userhz_jiffies -100 -HZ -100
On a kernel without the fix, at CONFIG_HZ=250:
# int_jiffies: got '-18372957097414713411', want '-1'
# int_ms_jiffies: got '-18446744069414585320', want '-1000'
# int_userhz_jiffies: got '-18446742229035144346', want '-100'
not ok 1 test_int_jiffies_negative
(paths shortened; the runner prints them under /proc/sys/debug/test_sysctl)
Signed-off-by: Zhan Xusheng <[email protected]>
---
tools/testing/selftests/sysctl/sysctl.sh | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/tools/testing/selftests/sysctl/sysctl.sh
b/tools/testing/selftests/sysctl/sysctl.sh
index ceb5cfa0cfd4..ad1ee0fccd7c 100755
--- a/tools/testing/selftests/sysctl/sysctl.sh
+++ b/tools/testing/selftests/sysctl/sysctl.sh
@@ -328,6 +328,29 @@ test_int_plain()
assert_int_range "$t" "$baseline" || RET=$KSFT_FAIL
}
+# The jiffies converters report the sign separately from the magnitude, so a
+# negative value must survive the round trip through the converter. Each
+# value below is chosen to convert exactly at every CONFIG_HZ.
+test_int_jiffies_negative()
+{
+ local t="${SYSCTL}/int_jiffies"
+ local m="${SYSCTL}/int_ms_jiffies"
+ local u="${SYSCTL}/int_userhz_jiffies"
+
+ [[ -f "$t" && -f "$m" && -f "$u" ]] || { RET=$KSFT_SKIP; return; }
+
+ printf '%s' "-1" > "$t"
+ assert_content "$t" "-1" || RET=$KSFT_FAIL
+ printf '%s' "-1000" > "$m"
+ assert_content "$m" "-1000" || RET=$KSFT_FAIL
+ printf '%s' "-100" > "$u"
+ assert_content "$u" "-100" || RET=$KSFT_FAIL
+
+ # The positive path was never broken; keep it covered.
+ printf '%s' "1" > "$t"
+ assert_content "$t" "1" || RET=$KSFT_FAIL
+}
+
test_uint_plain()
{
local t="${SYSCTL}/uint_0001"
--
2.43.0
