From 5d1854e15ee979f8e27330f0d3ce5e2703afa1dc Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Wed, 6 Dec 2006 20:33:06 -0800 Subject: [PATCH] [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)))) { 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 Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/swapfile.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 8e206cea0f..f315131db0 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1552,6 +1552,11 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags) error = -EINVAL; if (!maxpages) goto bad_swap; + if (swapfilesize && maxpages > swapfilesize) { + printk(KERN_WARNING + "Swap area shorter than signature indicates\n"); + goto bad_swap; + } if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) goto bad_swap; if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) @@ -1579,12 +1584,6 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags) goto bad_swap; } - if (swapfilesize && maxpages > swapfilesize) { - printk(KERN_WARNING - "Swap area shorter than signature indicates\n"); - error = -EINVAL; - goto bad_swap; - } if (nr_good_pages) { p->swap_map[0] = SWAP_MAP_BAD; p->max = maxpages; -- 2.39.5