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  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Fri, 21 Oct 2011 14:18:18 -0700
From:	"Darrick J. Wong" <djwong@...ibm.com>
To:	Tao Ma <tm@....ma>, Theodore Tso <tytso@....edu>
Cc:	linux-ext4@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH 4/5] ext4: Prevent stack overrun in ext4_file_open when
	recording last known mountpoint

In ext4_file_open, the filesystem records the mountpoint of the first file that
is opened after mounting the filesystem.  It does this by allocating a 64-byte
stack buffer, calling d_path() to grab the mount point through which this file
was accessed, and then memcpy()ing 64 bytes into the superblock's
s_last_mounted field, starting from the return value of d_path(), which is
stored as "cp".  However, if cp > buf (which it frequently is since path
components are prepended starting at the end of buf) then we can end up copying
stack data into the superblock.

Writing stack variables into the superblock doesn't sound like a great idea, so
use strlcpy instead.  Andi Kleen suggested using strlcpy instead of strncpy.

Signed-off-by: Darrick J. Wong <djwong@...ibm.com>
---
 fs/ext4/file.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)


diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index e4095e9..9781099 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -181,8 +181,8 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
 		path.dentry = mnt->mnt_root;
 		cp = d_path(&path, buf, sizeof(buf));
 		if (!IS_ERR(cp)) {
-			memcpy(sbi->s_es->s_last_mounted, cp,
-			       sizeof(sbi->s_es->s_last_mounted));
+			strlcpy(sbi->s_es->s_last_mounted, cp,
+				sizeof(sbi->s_es->s_last_mounted));
 			ext4_mark_super_dirty(sb);
 		}
 	}

--
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