Patchwork [1/1] eCryptfs: Infinite loop due to overflow in ecryptfs_write()

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Submitter Colin King
Date March 5, 2012, 2:07 p.m.
Message ID <1330956459-8692-2-git-send-email-colin.king@canonical.com>
Download mbox | patch
Permalink /patch/144681/
State New
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Comments

Colin King - March 5, 2012, 2:07 p.m.
From: Li Wang <liwang@nudt.edu.cn>

ecryptfs_write() can enter an infinite loop when truncating a file to a
size larger than 4G. This only happens on architectures where size_t is
represented by 32 bits.

This was caused by a size_t overflow due to it incorrectly being used to
store the result of a calculation which uses potentially large values of
type loff_t.

[tyhicks@canonical.com: rewrite subject and commit message]
Signed-off-by: Li Wang <liwang@nudt.edu.cn>
Signed-off-by: Yunchuan Wen <wenyunchuan@kylinos.com.cn>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Colin ian King <colin.king@canonical.com>
(cherry picked from commit 684a3ff7e69acc7c678d1a1394fe9e757993fd34)
---
 fs/ecryptfs/read_write.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
Herton Ronaldo Krzesinski - March 5, 2012, 2:24 p.m.
On Mon, Mar 05, 2012 at 02:07:39PM +0000, Colin King wrote:
> From: Li Wang <liwang@nudt.edu.cn>
> 
> ecryptfs_write() can enter an infinite loop when truncating a file to a
> size larger than 4G. This only happens on architectures where size_t is
> represented by 32 bits.
> 
> This was caused by a size_t overflow due to it incorrectly being used to
> store the result of a calculation which uses potentially large values of
> type loff_t.
> 
> [tyhicks@canonical.com: rewrite subject and commit message]
> Signed-off-by: Li Wang <liwang@nudt.edu.cn>
> Signed-off-by: Yunchuan Wen <wenyunchuan@kylinos.com.cn>
> Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
> Signed-off-by: Colin ian King <colin.king@canonical.com>
> (cherry picked from commit 684a3ff7e69acc7c678d1a1394fe9e757993fd34)
> ---
>  fs/ecryptfs/read_write.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
> index 3745f7c..ec3d936 100644
> --- a/fs/ecryptfs/read_write.c
> +++ b/fs/ecryptfs/read_write.c
> @@ -130,13 +130,13 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
>  		pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
>  		size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
>  		size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
> -		size_t total_remaining_bytes = ((offset + size) - pos);
> +		loff_t total_remaining_bytes = ((offset + size) - pos);
>  
>  		if (num_bytes > total_remaining_bytes)
>  			num_bytes = total_remaining_bytes;
>  		if (pos < offset) {
>  			/* remaining zeros to write, up to destination offset */
> -			size_t total_remaining_zeros = (offset - pos);
> +			loff_t total_remaining_zeros = (offset - pos);
>  
>  			if (num_bytes > total_remaining_zeros)
>  				num_bytes = total_remaining_zeros;
> -- 
> 1.7.9
> 
> 
> -- 
> kernel-team mailing list
> kernel-team@lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team
>
Stefan Bader - March 5, 2012, 3 p.m.
On 05.03.2012 15:07, Colin King wrote:
> From: Li Wang <liwang@nudt.edu.cn>
> 
> ecryptfs_write() can enter an infinite loop when truncating a file to a
> size larger than 4G. This only happens on architectures where size_t is
> represented by 32 bits.
> 
> This was caused by a size_t overflow due to it incorrectly being used to
> store the result of a calculation which uses potentially large values of
> type loff_t.
> 
> [tyhicks@canonical.com: rewrite subject and commit message]
> Signed-off-by: Li Wang <liwang@nudt.edu.cn>
> Signed-off-by: Yunchuan Wen <wenyunchuan@kylinos.com.cn>
> Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Tyler Hicks <tyhicks@canonical.com>

> Signed-off-by: Colin ian King <colin.king@canonical.com>
> (cherry picked from commit 684a3ff7e69acc7c678d1a1394fe9e757993fd34)

Maybe better switch around the picked and sob. So picked and then signed off?
Probably should have a bug link in there?

> ---
>  fs/ecryptfs/read_write.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
> index 3745f7c..ec3d936 100644
> --- a/fs/ecryptfs/read_write.c
> +++ b/fs/ecryptfs/read_write.c
> @@ -130,13 +130,13 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
>  		pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
>  		size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
>  		size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
> -		size_t total_remaining_bytes = ((offset + size) - pos);
> +		loff_t total_remaining_bytes = ((offset + size) - pos);
>  
>  		if (num_bytes > total_remaining_bytes)
>  			num_bytes = total_remaining_bytes;
>  		if (pos < offset) {
>  			/* remaining zeros to write, up to destination offset */
> -			size_t total_remaining_zeros = (offset - pos);
> +			loff_t total_remaining_zeros = (offset - pos);
>  
>  			if (num_bytes > total_remaining_zeros)
>  				num_bytes = total_remaining_zeros;

Patch

diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
index 3745f7c..ec3d936 100644
--- a/fs/ecryptfs/read_write.c
+++ b/fs/ecryptfs/read_write.c
@@ -130,13 +130,13 @@  int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
 		pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
 		size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
 		size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
-		size_t total_remaining_bytes = ((offset + size) - pos);
+		loff_t total_remaining_bytes = ((offset + size) - pos);
 
 		if (num_bytes > total_remaining_bytes)
 			num_bytes = total_remaining_bytes;
 		if (pos < offset) {
 			/* remaining zeros to write, up to destination offset */
-			size_t total_remaining_zeros = (offset - pos);
+			loff_t total_remaining_zeros = (offset - pos);
 
 			if (num_bytes > total_remaining_zeros)
 				num_bytes = total_remaining_zeros;