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aio: restore locking of ioctx list on removal

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Commit 36f5588905
"aio: refcounting cleanup" resulted in ioctx_lock not being held
during ctx removal, leaving the list susceptible to corruptions.

In mainline kernel the issue went away as a side effect of
db446a08c2 "aio: convert the ioctx list to
table lookup v3".

Fix the problem by restoring appropriate locking.

Signed-off-by: Mateusz Guzik <mguzik@redhat.com>
Reported-by: Eryu Guan <eguan@redhat.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Kent Overstreet <kmo@daterainc.com>
Acked-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mateusz Guzik 2013-12-05 11:09:02 +01:00 committed by Greg Kroah-Hartman
parent 604ae797e7
commit f8715e7d2a
1 changed files with 6 additions and 4 deletions
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10
fs/aio.c
View file

@ -423,10 +423,12 @@ static void kill_ioctx_rcu(struct rcu_head *head)
* when the processes owning a context have all exited to encourage
* the rapid destruction of the kioctx.
*/
static void kill_ioctx(struct kioctx *ctx)
static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx)
{
if (!atomic_xchg(&ctx->dead, 1)) {
spin_lock(&mm->ioctx_lock);
hlist_del_rcu(&ctx->list);
spin_unlock(&mm->ioctx_lock);
/*
* It'd be more correct to do this in free_ioctx(), after all
@ -494,7 +496,7 @@ void exit_aio(struct mm_struct *mm)
*/
ctx->mmap_size = 0;
kill_ioctx(ctx);
kill_ioctx(mm, ctx);
}
}
@ -852,7 +854,7 @@ SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
if (!IS_ERR(ioctx)) {
ret = put_user(ioctx->user_id, ctxp);
if (ret)
kill_ioctx(ioctx);
kill_ioctx(current->mm, ioctx);
put_ioctx(ioctx);
}
@ -870,7 +872,7 @@ SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
{
struct kioctx *ioctx = lookup_ioctx(ctx);
if (likely(NULL != ioctx)) {
kill_ioctx(ioctx);
kill_ioctx(current->mm, ioctx);
put_ioctx(ioctx);
return 0;
}