2006-02-08 06:50:47

by Chris Wright

Subject: [PATCH 13/23] Fix keyctl usage of strnlen_user()

-stable review patch. If anyone has any objections, please let us know.
------------------

In the small window between strnlen_user() and copy_from_user() userspace
could alter the terminating `\0' character.

Signed-off-by: Davi Arnaut <[email protected]>
Cc: David Howells <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Chris Wright <[email protected]>
---

security/keys/keyctl.c | 15 ++++++++++-----
1 files changed, 10 insertions(+), 5 deletions(-)

Index: linux-2.6.15.3/security/keys/keyctl.c
===================================================================
--- linux-2.6.15.3.orig/security/keys/keyctl.c
+++ linux-2.6.15.3/security/keys/keyctl.c
@@ -66,9 +66,10 @@ asmlinkage long sys_add_key(const char _
description = kmalloc(dlen + 1, GFP_KERNEL);
if (!description)
goto error;
+ description[dlen] = '\0';

ret = -EFAULT;
- if (copy_from_user(description, _description, dlen + 1) != 0)
+ if (copy_from_user(description, _description, dlen) != 0)
goto error2;

/* pull the payload in if one was supplied */
@@ -160,9 +161,10 @@ asmlinkage long sys_request_key(const ch
description = kmalloc(dlen + 1, GFP_KERNEL);
if (!description)
goto error;
+ description[dlen] = '\0';

ret = -EFAULT;
- if (copy_from_user(description, _description, dlen + 1) != 0)
+ if (copy_from_user(description, _description, dlen) != 0)
goto error2;

/* pull the callout info into kernel space */
@@ -181,9 +183,10 @@ asmlinkage long sys_request_key(const ch
callout_info = kmalloc(dlen + 1, GFP_KERNEL);
if (!callout_info)
goto error2;
+ callout_info[dlen] = '\0';

ret = -EFAULT;
- if (copy_from_user(callout_info, _callout_info, dlen + 1) != 0)
+ if (copy_from_user(callout_info, _callout_info, dlen) != 0)
goto error3;
}

@@ -278,9 +281,10 @@ long keyctl_join_session_keyring(const c
name = kmalloc(nlen + 1, GFP_KERNEL);
if (!name)
goto error;
+ name[nlen] = '\0';

ret = -EFAULT;
- if (copy_from_user(name, _name, nlen + 1) != 0)
+ if (copy_from_user(name, _name, nlen) != 0)
goto error2;
}

@@ -582,9 +586,10 @@ long keyctl_keyring_search(key_serial_t
description = kmalloc(dlen + 1, GFP_KERNEL);
if (!description)
goto error;
+ description[dlen] = '\0';

ret = -EFAULT;
- if (copy_from_user(description, _description, dlen + 1) != 0)
+ if (copy_from_user(description, _description, dlen) != 0)
goto error2;

/* get the keyring at which to begin the search */

--

2006-02-08 10:09:03

by David Howells

Subject: Re: [PATCH 13/23] Fix keyctl usage of strnlen_user()

Chris Wright <[email protected]> wrote:

> -stable review patch. If anyone has any objections, please let us know.

It looks fine by me.

David