From: Eric Sandeen <sandeen@redhat.com> Date: Tue, 29 Jul 2008 09:37:13 -0500 Subject: [fs] ecryptfs: use page_alloc to get a page of memory Message-id: 488F2B19.8040004@redhat.com O-Subject: [RHEL5.3 PATCH] ecryptfs: use page_alloc not kmalloc to get a page of memory Bugzilla: 457058 RH-Acked-by: Jeff Layton <jlayton@redhat.com> RH-Acked-by: Josef Bacik <jbacik@redhat.com> RH-Acked-by: Larry Woodman <lwoodman@redhat.com> For [Bug 457058] ecryptfs page-sized memory allocations can corrupt memory Thanks, -Eric From: Eric Sandeen <sandeen@redhat.com> Date: Mon, 28 Jul 2008 22:46:39 +0000 (-0700) Subject: eCryptfs: use page_alloc not kmalloc to get a page of memory X-Git-Tag: v2.6.27-rc1~8 X-Git-Url: http://git.engineering.redhat.com/?p=linux-2.6.git;a=commitdiff_plain;h=7fcba054373d5dfc43d26e243a5c9b92069972ee 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 38859f0..e8b6fbf 100644 --- a/fs/ecryptfs/crypto.c +++ b/fs/ecryptfs/crypto.c @@ -422,8 +422,8 @@ 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; @@ -439,14 +439,14 @@ 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++) { @@ -474,7 +474,10 @@ 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; } @@ -556,8 +559,8 @@ 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; @@ -574,14 +577,14 @@ 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++) { @@ -609,7 +612,10 @@ 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; }