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+ sys_semctl-fix-kernel-stack-leakage.patch added to -mm tree



The patch titled
     sys_semctl: fix kernel stack leakage
has been added to the -mm tree.  Its filename is
     sys_semctl-fix-kernel-stack-leakage.patch

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*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this

The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/

------------------------------------------------------
Subject: sys_semctl: fix kernel stack leakage
From: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>

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@xxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 ipc/sem.c |    2 ++
 1 file changed, 2 insertions(+)

diff -puN ipc/sem.c~sys_semctl-fix-kernel-stack-leakage ipc/sem.c
--- a/ipc/sem.c~sys_semctl-fix-kernel-stack-leakage
+++ a/ipc/sem.c
@@ -743,6 +743,8 @@ static unsigned long copy_semid_to_user(
 	    {
 		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;
_

Patches currently in -mm which might be from drosenberg@xxxxxxxxxxxxx are

origin.patch
sys_semctl-fix-kernel-stack-leakage.patch
drivers-serial-serial_corec-prevent-reading-uninitialized-stack-memory.patch
drivers-char-amiserialc-prevent-reading-uninitialized-stack-memory.patch
drivers-char-nozomic-prevent-reading-uninitialized-stack-memory.patch

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