lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date:	Sun,  4 Oct 2015 01:38:16 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	Theodore Ts'o <tytso@....edu>, stable@...r.kernel.org
Subject: [PATCH 1/5] ext4 crypto: fix memory leak in ext4_bio_write_page()

There are times when ext4_bio_write_page() is called even though we
don't actually need to do any I/O.  This happens when ext4_writepage()
gets called by the jbd2 commit path when an inode needs to force its
pages written out in order to provide data=ordered guarantees --- and
a page is backed by an unwritten (e.g., uninitialized) block on disk,
or if delayed allocation means the page's backing store hasn't been
allocated yet.  In that case, we need to skip the call to
ext4_encrypt_page(), since in addition to wasting CPU, it leads to a
bounce page and an ext4 crypto context getting leaked.

Signed-off-by: Theodore Ts'o <tytso@....edu>
Cc: stable@...r.kernel.org
---
 fs/ext4/page-io.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 84ba4d2..17fbe38 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -425,6 +425,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 	struct buffer_head *bh, *head;
 	int ret = 0;
 	int nr_submitted = 0;
+	int nr_to_submit = 0;
 
 	blocksize = 1 << inode->i_blkbits;
 
@@ -477,11 +478,13 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 		}
 		set_buffer_async_write(bh);
+		nr_to_submit++;
 	} while ((bh = bh->b_this_page) != head);
 
 	bh = head = page_buffers(page);
 
-	if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode)) {
+	if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode) &&
+	    nr_to_submit) {
 		data_page = ext4_encrypt(inode, page);
 		if (IS_ERR(data_page)) {
 			ret = PTR_ERR(data_page);
-- 
2.5.0

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Powered by blists - more mailing lists