This is a note to let you know that I've just added the patch titled aio: fix mremap after fork null-deref to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: aio-fix-mremap-after-fork-null-deref.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 81e9d6f8647650a7bead74c5f926e29970e834d1 Mon Sep 17 00:00:00 2001 From: Seth Jenkins <sethjenkins@xxxxxxxxxx> Date: Tue, 31 Jan 2023 12:25:55 -0500 Subject: aio: fix mremap after fork null-deref From: Seth Jenkins <sethjenkins@xxxxxxxxxx> 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@xxxxxxxxxx: fix 80 column issue] Link: https://lkml.kernel.org/r/x49sffq4nvg.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Fixes: e4a0d3e720e7 ("aio: Make it possible to remap aio ring") Signed-off-by: Seth Jenkins <sethjenkins@xxxxxxxxxx> Signed-off-by: Jeff Moyer <jmoyer@xxxxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Benjamin LaHaise <bcrl@xxxxxxxxx> Cc: Jann Horn <jannh@xxxxxxxxxx> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/aio.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/fs/aio.c +++ b/fs/aio.c @@ -361,6 +361,9 @@ static int aio_ring_mremap(struct vm_are 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_are } } +out_unlock: rcu_read_unlock(); spin_unlock(&mm->ioctx_lock); return res; Patches currently in stable-queue which might be from sethjenkins@xxxxxxxxxx are queue-6.1/aio-fix-mremap-after-fork-null-deref.patch