From 81e9d6f8647650a7bead74c5f926e29970e834d1 Mon Sep 17 00:00:00 2001 From: Seth Jenkins Date: Tue, 31 Jan 2023 12:25:55 -0500 Subject: aio: fix mremap after fork null-deref 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. [jmoyer@redhat.com: fix 80 column issue] Link: https://lkml.kernel.org/r/x49sffq4nvg.fsf@segfault.boston.devel.redhat.com Fixes: e4a0d3e720e7 ("aio: Make it possible to remap aio ring") Signed-off-by: Seth Jenkins Signed-off-by: Jeff Moyer Cc: Alexander Viro Cc: Benjamin LaHaise Cc: Jann Horn Cc: Pavel Emelyanov Cc: Signed-off-by: Andrew Morton --- fs/aio.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'fs') 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; -- cgit v1.2.3