[34-longterm 172/247] x86: Fix panic when handling "mem={invalid}" param

[Paul Gortmaker]

From: Kamal Mostafa <kamal@xxxxxxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit 77eed821accf5dd962b1f13bed0680e217e49112 upstream.

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@xxxxxxxxxxxxx>
BugLink: http://bugs.launchpad.net/bugs/553464
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Rafael J. Wysocki <rjw@xxxxxxx>
LKML-Reference: <1296783486-23033-1-git-send-email-kamal@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 arch/x86/kernel/e820.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 7bca3c6..4267f42 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -989,6 +989,9 @@ 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;
-- 
1.7.4.4

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