[3.11.y.z extended stable] Patch "efi-pstore: Fix an overflow on 32-bit builds" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    efi-pstore: Fix an overflow on 32-bit builds

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 696b27a6eb09cdf3bad21108e1f90b7a6716db46 Mon Sep 17 00:00:00 2001
From: Andrzej Zaborowski <andrew.zaborowski at intel.com>
Date: Mon, 9 Jun 2014 16:50:40 +0200
Subject: efi-pstore: Fix an overflow on 32-bit builds

commit 783ee43118dc773bc8b0342c5b230e017d5a04d0 upstream.

In generic_id the long int timestamp is multiplied by 100000 and needs
an explicit cast to u64.

Without that the id in the resulting pstore filename is wrong and
userspace may have problems parsing it, but more importantly files in
pstore can never be deleted and may fill the EFI flash (brick device?).
This happens because when generic pstore code wants to delete a file,
it passes the id to the EFI backend which reinterpretes it and a wrong
variable name is attempted to be deleted.  There's no error message but
after remounting pstore, deleted files would reappear.

Signed-off-by: Andrew Zaborowski <andrew.zaborowski at intel.com>
Acked-by: David Rientjes <rientjes at google.com>
Signed-off-by: Matt Fleming <matt.fleming at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/firmware/efi/efi-pstore.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
index b438a3a4d0d8..14e83e955182 100644
--- a/drivers/firmware/efi/efi-pstore.c
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -39,7 +39,7 @@ struct pstore_read_data {
 static inline u64 generic_id(unsigned long timestamp,
 			     unsigned int part, int count)
 {
-	return (timestamp * 100 + part) * 1000 + count;
+	return ((u64) timestamp * 100 + part) * 1000 + count;
 }

 static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
--
1.9.1