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>
---
fs/aio.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 5b2ff20ad322..74eae7de7323 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -361,16 +361,18 @@ static int aio_ring_mremap(struct vm_area_struct *vma)
spin_lock(&mm->ioctx_lock);
rcu_read_lock();
table = rcu_dereference(mm->ioctx_table);
- for (i = 0; i < table->nr; i++) {
- struct kioctx *ctx;
-
- ctx = rcu_dereference(table->table[i]);
- if (ctx && ctx->aio_ring_file == file) {
- if (!atomic_read(&ctx->dead)) {
- ctx->user_id = ctx->mmap_base = vma->vm_start;
- res = 0;
+ if (table) {
+ for (i = 0; i < table->nr; i++) {
+ struct kioctx *ctx;
+
+ ctx = rcu_dereference(table->table[i]);
+ if (ctx && ctx->aio_ring_file == file) {
+ if (!atomic_read(&ctx->dead)) {
+ ctx->user_id = ctx->mmap_base = vma->vm_start;
+ res = 0;
+ }
+ break;
}
- break;
}
}
--
2.38.1.431.g37b22c650d-goog
