Messages in this thread Patch in this message | | | From | Julien Grall <> | Subject | [PATCH] x86/xen: Remove undefined behavior in setup_features() | Date | Fri, 17 Jun 2022 11:30:37 +0100 |
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From: Julien Grall <jgrall@amazon.com>
1 << 31 is undefined. So switch to 1U << 31.
Fixes: 5ead97c84fa7 ("xen: Core Xen implementation") Signed-off-by: Julien Grall <jgrall@amazon.com>
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This was actually caught because I wasn't able to boot Linux 5.18 and onwards when built with GCC 7.3 and UBSAN enabled. There was no message but instead an early crash because the instruction "cli was used too early.
This issue has always been there but it only shows after Linux switched from C89 to C11. --- drivers/xen/features.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/xen/features.c b/drivers/xen/features.c index 7b591443833c..87f1828d40d5 100644 --- a/drivers/xen/features.c +++ b/drivers/xen/features.c @@ -42,7 +42,7 @@ void xen_setup_features(void) if (HYPERVISOR_xen_version(XENVER_get_features, &fi) < 0) break; for (j = 0; j < 32; j++) - xen_features[i * 32 + j] = !!(fi.submap & 1<<j); + xen_features[i * 32 + j] = !!(fi.submap & 1U << j); } if (xen_pv_domain()) { -- 2.32.0
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