eCryptfs: use page_alloc not kmalloc to get a page of memory
With SLUB debugging turned on in 2.6.26, I was getting memory corruption when testing eCryptfs. The root cause turned out to be that eCryptfs was doing kmalloc(PAGE_CACHE_SIZE); virt_to_page() and treating that as a nice page-aligned chunk of memory. But at least with SLUB debugging on, this is not always true, and the page we get from virt_to_page does not necessarily match the PAGE_CACHE_SIZE worth of memory we got from kmalloc. My simple testcase was 2 loops doing "rm -f fileX; cp /tmp/fileX ." for 2 different multi-megabyte files. With this change I no longer see the corruption. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Acked-by: Michael Halcrow <mhalcrow@us.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: <stable@kernel.org> [2.6.25.x, 2.6.26.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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25947d5ac5
commit
7fcba05437
1 changed files with 18 additions and 12 deletions
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@ -475,8 +475,8 @@ int ecryptfs_encrypt_page(struct page *page)
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{
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{
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struct inode *ecryptfs_inode;
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struct inode *ecryptfs_inode;
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struct ecryptfs_crypt_stat *crypt_stat;
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struct ecryptfs_crypt_stat *crypt_stat;
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char *enc_extent_virt = NULL;
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char *enc_extent_virt;
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struct page *enc_extent_page;
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struct page *enc_extent_page = NULL;
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loff_t extent_offset;
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loff_t extent_offset;
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int rc = 0;
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int rc = 0;
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@ -492,14 +492,14 @@ int ecryptfs_encrypt_page(struct page *page)
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page->index);
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page->index);
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goto out;
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goto out;
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}
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}
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enc_extent_virt = kmalloc(PAGE_CACHE_SIZE, GFP_USER);
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enc_extent_page = alloc_page(GFP_USER);
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if (!enc_extent_virt) {
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if (!enc_extent_page) {
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rc = -ENOMEM;
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rc = -ENOMEM;
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ecryptfs_printk(KERN_ERR, "Error allocating memory for "
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ecryptfs_printk(KERN_ERR, "Error allocating memory for "
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"encrypted extent\n");
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"encrypted extent\n");
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goto out;
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goto out;
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}
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}
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enc_extent_page = virt_to_page(enc_extent_virt);
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enc_extent_virt = kmap(enc_extent_page);
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for (extent_offset = 0;
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for (extent_offset = 0;
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extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
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extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
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extent_offset++) {
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extent_offset++) {
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@ -527,7 +527,10 @@ int ecryptfs_encrypt_page(struct page *page)
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}
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}
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}
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}
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out:
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out:
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kfree(enc_extent_virt);
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if (enc_extent_page) {
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kunmap(enc_extent_page);
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__free_page(enc_extent_page);
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}
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return rc;
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return rc;
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}
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}
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@ -609,8 +612,8 @@ int ecryptfs_decrypt_page(struct page *page)
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{
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{
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struct inode *ecryptfs_inode;
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struct inode *ecryptfs_inode;
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struct ecryptfs_crypt_stat *crypt_stat;
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struct ecryptfs_crypt_stat *crypt_stat;
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char *enc_extent_virt = NULL;
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char *enc_extent_virt;
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struct page *enc_extent_page;
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struct page *enc_extent_page = NULL;
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unsigned long extent_offset;
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unsigned long extent_offset;
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int rc = 0;
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int rc = 0;
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@ -627,14 +630,14 @@ int ecryptfs_decrypt_page(struct page *page)
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page->index);
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page->index);
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goto out;
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goto out;
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}
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}
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enc_extent_virt = kmalloc(PAGE_CACHE_SIZE, GFP_USER);
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enc_extent_page = alloc_page(GFP_USER);
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if (!enc_extent_virt) {
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if (!enc_extent_page) {
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rc = -ENOMEM;
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rc = -ENOMEM;
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ecryptfs_printk(KERN_ERR, "Error allocating memory for "
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ecryptfs_printk(KERN_ERR, "Error allocating memory for "
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"encrypted extent\n");
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"encrypted extent\n");
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goto out;
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goto out;
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}
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}
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enc_extent_page = virt_to_page(enc_extent_virt);
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enc_extent_virt = kmap(enc_extent_page);
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for (extent_offset = 0;
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for (extent_offset = 0;
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extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
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extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
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extent_offset++) {
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extent_offset++) {
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@ -662,7 +665,10 @@ int ecryptfs_decrypt_page(struct page *page)
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}
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}
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}
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}
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out:
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out:
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kfree(enc_extent_virt);
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if (enc_extent_page) {
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kunmap(enc_extent_page);
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__free_page(enc_extent_page);
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}
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return rc;
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return rc;
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}
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}
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