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vfs: ensure page symlinks are NUL-terminated
On-disk data corruption could cause a page link to have its i_size set to PAGE_SIZE (or a multiple thereof) and its contents all non-NUL. NUL-terminate the link name to ensure this doesn't cause further problems for the kernel. Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Duane Griffin <duaneg@dghda.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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@ -2786,13 +2786,16 @@ int vfs_follow_link(struct nameidata *nd, const char *link)
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/* get the link contents into pagecache */
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static char *page_getlink(struct dentry * dentry, struct page **ppage)
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{
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struct page * page;
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char *kaddr;
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struct page *page;
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struct address_space *mapping = dentry->d_inode->i_mapping;
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page = read_mapping_page(mapping, 0, NULL);
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if (IS_ERR(page))
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return (char*)page;
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*ppage = page;
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return kmap(page);
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kaddr = kmap(page);
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nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
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return kaddr;
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}
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int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
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