[Dapper/Hardy/Karmic/Maverick] [CVE-2010-4083] [PATCH 1/1] sys_semctl: fix kernel stack leakage, CVE-2010-4083

Tim Gardner tim.gardner at canonical.com
Fri Feb 4 19:46:58 UTC 2011


On 02/04/2011 10:26 AM, Brad Figg wrote:
> From: Dan Rosenberg<drosenberg at vsecurity.com>
>
> CVE-2010-4083
>
> BugLink: http://bugs.launchpad.net/bugs/712749
>
> The semctl syscall has several code paths that lead to the leakage of
> uninitialized kernel stack memory (namely the IPC_INFO, SEM_INFO,
> IPC_STAT, and SEM_STAT commands) during the use of the older, obsolete
> version of the semid_ds struct.
>
> The copy_semid_to_user() function declares a semid_ds struct on the stack
> and copies it back to the user without initializing or zeroing the
> "sem_base", "sem_pending", "sem_pending_last", and "undo" pointers,
> allowing the leakage of 16 bytes of kernel stack memory.
>
> The code is still reachable on 32-bit systems - when calling semctl()
> newer glibc's automatically OR the IPC command with the IPC_64 flag, but
> invoking the syscall directly allows users to use the older versions of
> the struct.
>
> Signed-off-by: Dan Rosenberg<dan.j.rosenberg at gmail.com>
> Cc: Manfred Spraul<manfred at colorfullife.com>
> Signed-off-by: Andrew Morton<akpm at linux-foundation.org>
> Signed-off-by: Linus Torvalds<torvalds at linux-foundation.org>
>
> (cherry-picked from commit 982f7c2b2e6a28f8f266e075d92e19c0dd4c6e56)
> Signed-off-by: Brad Figg<brad.figg at canonical.com>
> ---
>   ipc/sem.c |    2 ++
>   1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/ipc/sem.c b/ipc/sem.c
> index 40a8f46..0e0d49b 100644
> --- a/ipc/sem.c
> +++ b/ipc/sem.c
> @@ -743,6 +743,8 @@ static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in,
>   	    {
>   		struct semid_ds out;
>
> +		memset(&out, 0, sizeof(out));
> +
>   		ipc64_perm_to_ipc_perm(&in->sem_perm,&out.sem_perm);
>
>   		out.sem_otime	= in->sem_otime;

Acked-by: Tim Gardner <tim.gardner at canonical.com>

-- 
Tim Gardner tim.gardner at canonical.com



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