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authorKees Cook <keescook@chromium.org>2023-06-30 09:46:17 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2023-06-30 09:04:01 -0700
commitb69f0aeb068980af983d399deafc7477cec8bc04 (patch)
tree9ed5c782849059b2cc6bccde1306b8bd908d51f4 /kernel
parent112e7e21519422b6f2bb0fa8061f5685e9757170 (diff)
pid: Replace struct pid 1-element array with flex-array
For pid namespaces, struct pid uses a dynamically sized array member, "numbers". This was implemented using the ancient 1-element fake flexible array, which has been deprecated for decades. Replace it with a C99 flexible array, refactor the array size calculations to use struct_size(), and address elements via indexes. Note that the static initializer (which defines a single element) works as-is, and requires no special handling. Without this, CONFIG_UBSAN_BOUNDS (and potentially CONFIG_FORTIFY_SOURCE) will trigger bounds checks: https://lore.kernel.org/lkml/20230517-bushaltestelle-super-e223978c1ba6@brauner Cc: Christian Brauner <brauner@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jeff Xu <jeffxu@google.com> Cc: Andreas Gruenbacher <agruenba@redhat.com> Cc: Daniel Verkamp <dverkamp@chromium.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Jeff Xu <jeffxu@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Frederic Weisbecker <frederic@kernel.org> Reported-by: syzbot+ac3b41786a2d0565b6d5@syzkaller.appspotmail.com [brauner: dropped unrelated changes and remove 0 with NULL cast] Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/pid.c7
-rw-r--r--kernel/pid_namespace.c2
2 files changed, 6 insertions, 3 deletions
diff --git a/kernel/pid.c b/kernel/pid.c
index f93954a0384d..8bce3aebc949 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -656,8 +656,11 @@ void __init pid_idr_init(void)
idr_init(&init_pid_ns.idr);
- init_pid_ns.pid_cachep = KMEM_CACHE(pid,
- SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
+ init_pid_ns.pid_cachep = kmem_cache_create("pid",
+ struct_size((struct pid *)NULL, numbers, 1),
+ __alignof__(struct pid),
+ SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT,
+ NULL);
}
static struct file *__pidfd_fget(struct task_struct *task, int fd)
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index b43eee07b00c..70a929784a5d 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -48,7 +48,7 @@ static struct kmem_cache *create_pid_cachep(unsigned int level)
return kc;
snprintf(name, sizeof(name), "pid_%u", level + 1);
- len = sizeof(struct pid) + level * sizeof(struct upid);
+ len = struct_size((struct pid *)NULL, numbers, level + 1);
mutex_lock(&pid_caches_mutex);
/* Name collision forces to do allocation under mutex. */
if (!*pkc)