From: Seth Jenkins <sethjenkins@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Signed-off-by: Seth Jenkins <sethjenkins@xxxxxxxxxx>
[JEM: fixed 80 column issue]
Signed-off-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
---
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;
