aio: Fix null ptr deref in aio_complete() wakeup

list_del_init_careful() needs to be the last access to the wait queue
entry - it effectively unlocks access.

Previously, finish_wait() would see the empty list head and skip taking
the lock, and then we'd return - but the completion path would still
attempt to do the wakeup after the task_struct pointer had been
overwritten.

Fixes: 71eb6b6b0b ("fs/aio: obey min_nr when doing wakeups")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/linux-fsdevel/CAHTA-ubfwwB51A5Wg5M6H_rPEQK9pNf8FkAGH=vr=FEkyRrtqw@mail.gmail.com/
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Link: https://lore.kernel.org/stable/20240331215212.522544-1-kent.overstreet%40linux.dev
Link: https://lore.kernel.org/r/20240331215212.522544-1-kent.overstreet@linux.dev
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Kent Overstreet 2024-03-31 17:52:12 -04:00 committed by Christian Brauner
parent 22650a9982
commit caeb4b0a11
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@ -1202,8 +1202,8 @@ static void aio_complete(struct aio_kiocb *iocb)
spin_lock_irqsave(&ctx->wait.lock, flags); spin_lock_irqsave(&ctx->wait.lock, flags);
list_for_each_entry_safe(curr, next, &ctx->wait.head, w.entry) list_for_each_entry_safe(curr, next, &ctx->wait.head, w.entry)
if (avail >= curr->min_nr) { if (avail >= curr->min_nr) {
list_del_init_careful(&curr->w.entry);
wake_up_process(curr->w.private); wake_up_process(curr->w.private);
list_del_init_careful(&curr->w.entry);
} }
spin_unlock_irqrestore(&ctx->wait.lock, flags); spin_unlock_irqrestore(&ctx->wait.lock, flags);
} }