From caeb4b0a11b3393e43f7fa8e0a5a18462acc66bd Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Sun, 31 Mar 2024 17:52:12 -0400
Subject: [PATCH] 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: 71eb6b6b0ba9 ("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>
---
fs/aio.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/aio.c b/fs/aio.c
index 9cdaa2faa5363..0f4f531c97800 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1202,8 +1202,8 @@ static void aio_complete(struct aio_kiocb *iocb)
spin_lock_irqsave(&ctx->wait.lock, flags);
list_for_each_entry_safe(curr, next, &ctx->wait.head, w.entry)
if (avail >= curr->min_nr) {
- list_del_init_careful(&curr->w.entry);
wake_up_process(curr->w.private);
+ list_del_init_careful(&curr->w.entry);
}
spin_unlock_irqrestore(&ctx->wait.lock, flags);
}
--
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