ipc: add missing container_of()s for randstruct
When building with the randstruct gcc plugin, the layout of the IPC
structs will be randomized, which requires any sub-structure accesses to
use container_of(). The proc display handlers were missing the needed
container_of()s since the iterator is passing in the top-level struct
kern_ipc_perm.
This would lead to crashes when running the "lsipc" program after the
system had IPC registered (e.g. after starting up Gnome):
general protection fault: 0000 [#1] PREEMPT SMP
...
RIP: 0010:shm_add_rss_swap.isra.1+0x13/0xa0
...
Call Trace:
sysvipc_shm_proc_show+0x5e/0x150
sysvipc_proc_show+0x1a/0x30
seq_read+0x2e9/0x3f0
...
Link: http://lkml.kernel.org/r/20170730205950.GA55841@beast
Fixes: 3859a271a003 ("randstruct: Mark various structs for randomization")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/ipc/shm.c b/ipc/shm.c
index 28a4448..8828b4c 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -1380,9 +1380,11 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
{
struct user_namespace *user_ns = seq_user_ns(s);
- struct shmid_kernel *shp = it;
+ struct kern_ipc_perm *ipcp = it;
+ struct shmid_kernel *shp;
unsigned long rss = 0, swp = 0;
+ shp = container_of(ipcp, struct shmid_kernel, shm_perm);
shm_add_rss_swap(shp, &rss, &swp);
#if BITS_PER_LONG <= 32