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>
diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 7b99917..06db79d 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -475,8 +475,8 @@
{
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 @@
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 @@
}
}
out:
- kfree(enc_extent_virt);
+ if (enc_extent_page) {
+ kunmap(enc_extent_page);
+ __free_page(enc_extent_page);
+ }
return rc;
}
@@ -609,8 +612,8 @@
{
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 @@
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 @@
}
}
out:
- kfree(enc_extent_virt);
+ if (enc_extent_page) {
+ kunmap(enc_extent_page);
+ __free_page(enc_extent_page);
+ }
return rc;
}