From 81e9d6f8647650a7bead74c5f926e29970e834d1 Mon Sep 17 00:00:00 2001
From: Seth Jenkins <sethjenkins@google.com>
Date: Tue, 31 Jan 2023 12:25:55 -0500
Subject: [PATCH] aio: fix mremap after fork null-deref
Git-commit: 81e9d6f8647650a7bead74c5f926e29970e834d1
Patch-mainline: v6.2
References: git-fixes CVE-2023-52646 bsc#1223432
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>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>
---
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;
--
2.43.0