This is a note to let you know that I've just added the patch titled
swapfile: fix memory corruption via malformed swapfile
to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
swapfile-fix-memory-corruption-via-malformed-swapfile.patch
and it can be found in the queue-4.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From dd111be69114cc867f8e826284559bfbc1c40e37 Mon Sep 17 00:00:00 2001
From: Jann Horn <jann@xxxxxxxxx>
Date: Thu, 10 Nov 2016 10:46:19 -0800
Subject: swapfile: fix memory corruption via malformed swapfile
From: Jann Horn <jann@xxxxxxxxx>
commit dd111be69114cc867f8e826284559bfbc1c40e37 upstream.
When root activates a swap partition whose header has the wrong
endianness, nr_badpages elements of badpages are swabbed before
nr_badpages has been checked, leading to a buffer overrun of up to 8GB.
This normally is not a security issue because it can only be exploited
by root (more specifically, a process with CAP_SYS_ADMIN or the ability
to modify a swap file/partition), and such a process can already e.g.
modify swapped-out memory of any other userspace process on the system.
Link: http://lkml.kernel.org/r/1477949533-2509-1-git-send-email-jann@xxxxxxxxx
Signed-off-by: Jann Horn <jann@xxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Jerome Marchand <jmarchan@xxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 2 ++
1 file changed, 2 insertions(+)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2218,6 +2218,8 @@ static unsigned long read_swap_header(st
swab32s(&swap_header->info.version);
swab32s(&swap_header->info.last_page);
swab32s(&swap_header->info.nr_badpages);
+ if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
+ return 0;
for (i = 0; i < swap_header->info.nr_badpages; i++)
swab32s(&swap_header->info.badpages[i]);
}
Patches currently in stable-queue which might be from jann@xxxxxxxxx are
queue-4.8/swapfile-fix-memory-corruption-via-malformed-swapfile.patch
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