Messages in this thread Patch in this message | | | From | Paul Gortmaker <> | Subject | [34-longterm 045/209] sys_semctl: fix kernel stack leakage | Date | Thu, 14 Apr 2011 13:41:15 -0400 |
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From: Dan Rosenberg <drosenberg@vsecurity.com>
===================================================================== | This is a commit scheduled for the next v2.6.34 longterm release. | | If you see a problem with using this for longterm, please comment.| =====================================================================
commit 982f7c2b2e6a28f8f266e075d92e19c0dd4c6e56 upstream.
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@gmail.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- ipc/sem.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c index dbef95b..b4c1641 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -608,6 +608,8 @@ 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; -- 1.7.4.4
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