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eCryptfs: use page_alloc not kmalloc to get a page of memory

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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>
This commit is contained in:
Eric Sandeen 2008-07-28 15:46:39 -07:00 committed by Linus Torvalds
parent 25947d5ac5
commit 7fcba05437
1 changed files with 18 additions and 12 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

30
fs/ecryptfs/crypto.c
View file

@ -475,8 +475,8 @@ int ecryptfs_encrypt_page(struct page *page)
{
struct inode *ecryptfs_inode;
struct ecryptfs_crypt_stat *crypt_stat;
char *enc_extent_virt = NULL;
struct page *enc_extent_page;
char *enc_extent_virt;
struct page *enc_extent_page = NULL;
loff_t extent_offset;
int rc = 0;
@ -492,14 +492,14 @@ int ecryptfs_encrypt_page(struct page *page)
page->index);
goto out;
}
enc_extent_virt = kmalloc(PAGE_CACHE_SIZE, GFP_USER);
if (!enc_extent_virt) {
enc_extent_page = alloc_page(GFP_USER);
if (!enc_extent_page) {
rc = -ENOMEM;
ecryptfs_printk(KERN_ERR, "Error allocating memory for "
"encrypted extent\n");
goto out;
}
enc_extent_page = virt_to_page(enc_extent_virt);
enc_extent_virt = kmap(enc_extent_page);
for (extent_offset = 0;
extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
extent_offset++) {
@ -527,7 +527,10 @@ int ecryptfs_encrypt_page(struct page *page)
}
}
out:
kfree(enc_extent_virt);
if (enc_extent_page) {
kunmap(enc_extent_page);
__free_page(enc_extent_page);
}
return rc;
}
@ -609,8 +612,8 @@ int ecryptfs_decrypt_page(struct page *page)
{
struct inode *ecryptfs_inode;
struct ecryptfs_crypt_stat *crypt_stat;
char *enc_extent_virt = NULL;
struct page *enc_extent_page;
char *enc_extent_virt;
struct page *enc_extent_page = NULL;
unsigned long extent_offset;
int rc = 0;
@ -627,14 +630,14 @@ int ecryptfs_decrypt_page(struct page *page)
page->index);
goto out;
}
enc_extent_virt = kmalloc(PAGE_CACHE_SIZE, GFP_USER);
if (!enc_extent_virt) {
enc_extent_page = alloc_page(GFP_USER);
if (!enc_extent_page) {
rc = -ENOMEM;
ecryptfs_printk(KERN_ERR, "Error allocating memory for "
"encrypted extent\n");
goto out;
}
enc_extent_page = virt_to_page(enc_extent_virt);
enc_extent_virt = kmap(enc_extent_page);
for (extent_offset = 0;
extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
extent_offset++) {
@ -662,7 +665,10 @@ int ecryptfs_decrypt_page(struct page *page)
}
}
out:
kfree(enc_extent_virt);
if (enc_extent_page) {
kunmap(enc_extent_page);
__free_page(enc_extent_page);
}
return rc;
}