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aio: fix mremap after fork null-deref 

commit 81e9d6f864 upstream.

Commit e4a0d3e720 ("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: e4a0d3e720 ("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>
This commit is contained in:
Seth Jenkins 2023-01-31 12:25:55 -05:00 committed by Greg Kroah-Hartman
parent dc62f8f2cd
commit 808f1e4b57
1 changed files with 4 additions and 0 deletions
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4
fs/aio.c
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@ -328,6 +328,9 @@ 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;
@ -341,6 +344,7 @@ static int aio_ring_mremap(struct vm_area_struct *vma)
}
}
out_unlock:
rcu_read_unlock();
spin_unlock(&mm->ioctx_lock);
return res;