From: Seth Jenkins sethjenkins@google.com
Commit e4a0d3e720e7 ("aio: Make it possible to remap aio ring") introduced a null-deref if mremap is called on an old aio mapping after fork as mm->ioctx_table will be set to NULL.
Fixes: e4a0d3e720e7 ("aio: Make it possible to remap aio ring") Cc: stable@vger.kernel.org Signed-off-by: Seth Jenkins sethjenkins@google.com [JEM: fixed 80 column issue] Signed-off-by: Jeff Moyer jmoyer@redhat.com --- This passes the libaio test harness and fstests ./check -g aio. I also wrote a targeted test program and verified the issue was fixed.
fs/aio.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/fs/aio.c b/fs/aio.c index 562916d85cba..e85ba0b77f59 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -361,6 +361,9 @@ static int aio_ring_mremap(struct vm_area_struct *vma) spin_lock(&mm->ioctx_lock); rcu_read_lock(); table = rcu_dereference(mm->ioctx_table); + if (!table) + goto out_unlock; + for (i = 0; i < table->nr; i++) { struct kioctx *ctx;
@@ -374,6 +377,7 @@ static int aio_ring_mremap(struct vm_area_struct *vma) } }
+out_unlock: rcu_read_unlock(); spin_unlock(&mm->ioctx_lock); return res;