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| author | Dan Rosenberg <drosenberg@vsecurity.com> | 2010-09-30 15:15:31 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-01 10:50:58 -0700 |
| commit | 982f7c2b2e6a28f8f266e075d92e19c0dd4c6e56 (patch) | |
| tree | a25ab8534b9f43cb90292ed125dfb9d72fee9858 /ipc/sem.c | |
| parent | 64aab720bdf8771214a7c88872bd8e3194c2d279 (diff) | |
| download | lwn-982f7c2b2e6a28f8f266e075d92e19c0dd4c6e56.tar.gz lwn-982f7c2b2e6a28f8f266e075d92e19c0dd4c6e56.zip | |
sys_semctl: fix kernel stack leakage
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>
Diffstat (limited to 'ipc/sem.c')
| -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 40a8f462a822..0e0d49bbb867 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; |