[PATCH 4.18 038/350] x86/corruption-check: Fix panic in memory_corruption_check() when boot option without value is provided

Greg Kroah-Hartman
2018-11-11T23:42:36Z

From: He Zhe <zhe.he@windriver.com>

commit ccde460b9ae5c2bd5e4742af0a7f623c2daad566 upstream.

memory_corruption_check[{_period|_size}]()'s handlers do not check input
argument before passing it to kstrtoul() or simple_strtoull(). The argument
would be a NULL pointer if each of the kernel parameters, without its
value, is set in command line and thus cause the following panic.

PANIC: early exception 0xe3 IP 10:ffffffff73587c22 error 0 cr2 0x0
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.18-rc8+ #2
[ 0.000000] RIP: 0010:kstrtoull+0x2/0x10
...
[ 0.000000] Call Trace
[ 0.000000] ? set_corruption_check+0x21/0x49
[ 0.000000] ? do_early_param+0x4d/0x82
[ 0.000000] ? parse_args+0x212/0x330
[ 0.000000] ? rdinit_setup+0x26/0x26
[ 0.000000] ? parse_early_options+0x20/0x23
[ 0.000000] ? rdinit_setup+0x26/0x26
[ 0.000000] ? parse_early_param+0x2d/0x39
[ 0.000000] ? setup_arch+0x2f7/0xbf4
[ 0.000000] ? start_kernel+0x5e/0x4c2
[ 0.000000] ? load_ucode_bsp+0x113/0x12f
[ 0.000000] ? secondary_startup_64+0xa5/0xb0

This patch adds checks to prevent the panic.

Signed-off-by: He Zhe <zhe.he@windriver.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: gregkh@linuxfoundation.org
Cc: kstewart@linuxfoundation.org
Cc: pombredanne@nexb.com
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1534260823-87917-1-git-send-email-zhe.he@windriver.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/check.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)

--- a/arch/x86/kernel/check.c
+++ b/arch/x86/kernel/check.c
@@ -31,6 +31,11 @@ static __init int set_corruption_check(c
ssize_t ret;
unsigned long val;

+ if (!arg) {
+ pr_err("memory_corruption_check config string not provided\n");
+ return -EINVAL;
+ }
+
ret = kstrtoul(arg, 10, &val);
if (ret)
return ret;
@@ -45,6 +50,11 @@ static __init int set_corruption_check_p
ssize_t ret;
unsigned long val;

+ if (!arg) {
+ pr_err("memory_corruption_check_period config string not provided\n");
+ return -EINVAL;
+ }
+
ret = kstrtoul(arg, 10, &val);
if (ret)
return ret;
@@ -59,6 +69,11 @@ static __init int set_corruption_check_s
char *end;
unsigned size;

+ if (!arg) {
+ pr_err("memory_corruption_check_size config string not provided\n");
+ return -EINVAL;
+ }
+
size = memparse(arg, &end);

if (*end == '\0')