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authorDan Rosenberg <drosenberg@vsecurity.com>2010-09-30 22:15:31 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-01 17:50:58 (GMT)
commit982f7c2b2e6a28f8f266e075d92e19c0dd4c6e56 (patch)
treea25ab8534b9f43cb90292ed125dfb9d72fee9858 /ipc
parent64aab720bdf8771214a7c88872bd8e3194c2d279 (diff)
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')
-rw-r--r--ipc/sem.c2
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;

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