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authorPavel Emelyanov <xemul@openvz.org>2007-09-18 22:46:45 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-09-19 11:24:18 -0700
commit28f300d23674fa01ae747c66ce861d4ee6aebe8c (patch)
tree52ea69a57a89760d7060597690cb289d049eb4d0 /include
parent735de2230f09741077a645a913de0a04b10208bf (diff)
downloadlinux-linaro-28f300d23674fa01ae747c66ce861d4ee6aebe8c.tar.gz
Fix user namespace exiting OOPs
It turned out, that the user namespace is released during the do_exit() in exit_task_namespaces(), but the struct user_struct is released only during the put_task_struct(), i.e. MUCH later. On debug kernels with poisoned slabs this will cause the oops in uid_hash_remove() because the head of the chain, which resides inside the struct user_namespace, will be already freed and poisoned. Since the uid hash itself is required only when someone can search it, i.e. when the namespace is alive, we can safely unhash all the user_struct-s from it during the namespace exiting. The subsequent free_uid() will complete the user_struct destruction. For example simple program #include <sched.h> char stack[2 * 1024 * 1024]; int f(void *foo) { return 0; } int main(void) { clone(f, stack + 1 * 1024 * 1024, 0x10000000, 0); return 0; } run on kernel with CONFIG_USER_NS turned on will oops the kernel immediately. This was spotted during OpenVZ kernel testing. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org> Acked-by: "Serge E. Hallyn" <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/sched.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6239bc2c2ba..5445eaec690 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1472,6 +1472,7 @@ static inline struct user_struct *get_uid(struct user_struct *u)
}
extern void free_uid(struct user_struct *);
extern void switch_uid(struct user_struct *);
+extern void release_uids(struct user_namespace *ns);
#include <asm/current.h>