* [PATCH][v2] aio: fix mremap after fork null-deref
@ 2023-01-31 17:25 Jeff Moyer
0 siblings, 0 replies; only message in thread
From: Jeff Moyer @ 2023-01-31 17:25 UTC (permalink / raw)
To: Seth Jenkins, Alexander Viro, Benjamin LaHaise, Andrew Morton
Cc: linux-fsdevel, linux-aio, linux-kernel, Jann Horn,
Pavel Emelyanov, stable
From: Seth Jenkins <sethjenkins@google.com>
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@vger.kernel.org
Signed-off-by: Seth Jenkins <sethjenkins@google.com>
[JEM: fixed 80 column issue]
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
---
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;
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2023-01-31 17:25 [PATCH][v2] aio: fix mremap after fork null-deref Jeff Moyer
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