From: Seth Jenkins <sethjenkins@google.com> stable inclusion from stable-v4.19.273 commit d8dca1bfe9adcae38b35add64977818c0c13dd22 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6KOHU CVE: NA -------------------------------- commit 81e9d6f8647650a7bead74c5f926e29970e834d1 upstream. 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 <sethjenkins@google.com> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Jann Horn <jannh@google.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com> --- fs/aio.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/aio.c b/fs/aio.c index d221260b8f30..b77f0959f0e8 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -332,6 +332,9 @@ 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; @@ -345,6 +348,7 @@ static int aio_ring_mremap(struct vm_area_struct *vma) } } +out_unlock: rcu_read_unlock(); spin_unlock(&mm->ioctx_lock); return res; -- 2.25.1