diff options
| author | Dan Rosenberg <drosenberg@vsecurity.com> | 2010-09-30 15:15:31 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-12-09 13:24:17 -0800 |
| commit | ff63490293484aa5f62268fc46e34645c07c483a (patch) | |
| tree | 5f61832e8656e8db29f52125582606ba3fc91f46 | |
| parent | 77f5c399311bd4a6d8836dbd788dd0e45a582d15 (diff) | |
| download | lwn-ff63490293484aa5f62268fc46e34645c07c483a.tar.gz lwn-ff63490293484aa5f62268fc46e34645c07c483a.zip | |
sys_semctl: fix kernel stack leakage
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: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | ipc/sem.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index 0c0b28ece0cc..0cd0c5111df7 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -560,6 +560,8 @@ 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; |