[PATCH 4/5] x86/setup/crash: Check memblock_reserve() retval

[Borislav Petkov <bp@alien8.de>]

From: Borislav Petkov <bp@suse.de>

memblock_reserve() can fail but the crashkernel reservation code
doesn't check that and this can lead the user into believing that the
crashkernel region was actually reserved. Make sure we check that return
value and we exit early with a failure message in the error case.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Young <dyoung@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: jerry_hoemann@hp.com
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: WANG Chao <chaowang@redhat.com>
Cc: x86-ml <x86@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/kernel/setup.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index d4788719a1e2..3f75297d5fd0 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -531,7 +531,11 @@ static int __init reserve_crashkernel_low(void)
 		return -ENOMEM;
 	}
 
-	memblock_reserve(low_base, low_size);
+	ret = memblock_reserve(low_base, low_size);
+	if (ret) {
+		pr_err("%s: Error reserving crashkernel low memblock.\n", __func__);
+		return ret;
+	}
 
 	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
 		(unsigned long)(low_size >> 20),
@@ -589,7 +593,11 @@ static void __init reserve_crashkernel(void)
 			return;
 		}
 	}
-	memblock_reserve(crash_base, crash_size);
+	ret = memblock_reserve(crash_base, crash_size);
+	if (ret) {
+		pr_err("%s: Error reserving crashkernel memblock.\n", __func__);
+		return;
+	}
 
 	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
 		memblock_free(crash_base, crash_size);
-- 
2.3.5