From: Eric Sandeen <sandeen@redhat.com>
Date: Thu, 7 Dec 2006 04:33:06 +0000 (-0800)
Subject: [PATCH] reject corrupt swapfiles earlier
X-Git-Tag: v2.6.20-rc1~145^2^2~315
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5d1854e15ee979f8e27330f0d3ce5e2703afa1dc;p=pandora-kernel.git

[PATCH] reject corrupt swapfiles earlier

The fsfuzzer found this; with a corrupt small swapfile that claims to have
many pages:

  [root]# file swap.741.img
  swap.741.img: Linux/i386 swap file (new style) 1 (4K pages) size 1040191487 pages
  [root]# ls -l swap.741.img
  -rw-r--r-- 1 root root 16777216 Nov 22 05:18 swap.741.img

sys_swapon() will try to vmalloc all those pages, and -then- check to see if
the file is actually that large:

                if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) {
  <snip>
        if (swapfilesize && maxpages > swapfilesize) {
                printk(KERN_WARNING
                       "Swap area shorter than signature indicates\n");

It seems to me that it would make more sense to move this test up before
the vmalloc, with the other checks, to avoid the OOM-killer in this
situation...

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

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