x86: Fix panic when handling "mem={invalid}" param

Avoid removing all of memory and panicing when "mem={invalid}"
is specified, e.g. mem=blahblah, mem=0, or mem=nopentium (on
platforms other than x86_32).

Signed-off-by: Kamal Mostafa <kamal@canonical.com>
BugLink: http://bugs.launchpad.net/bugs/553464
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: <stable@kernel.org> # .3x: as far back as it applies
LKML-Reference: <1296783486-23033-1-git-send-email-kamal@canonical.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 294f26da0c0c..55a59d889dbd 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -856,6 +856,9 @@ static int __init parse_memopt(char *p)
 
         userdef = 1;
         mem_size = memparse(p, &p);
+        /* don't remove all of memory when handling "mem={invalid}" param */
+        if (mem_size == 0)
+                return -EINVAL;
         e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1);
 
         return 0;