linux-kernel - [PATCH] afs: Fix poential UAF in afs_make

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Date:   Fri, 30 Dec 2022 00:40:29 +0800
From:   Zheng Wang <zyytlz.wz@....com>
To:     dhowells@...hat.com
Cc:     marc.dionne@...istor.com, linux-afs@...ts.infradead.org,
        linux-kernel@...r.kernel.org, hackerzheng666@...il.com,
        alex000young@...il.com, security@...nel.org,
        Zheng Wang <zyytlz.wz@....com>
Subject: [PATCH] afs: Fix poential UAF in afs_make_call

There is a function call : afs_fs_get_capabilities calls afs_make_call, in
afs_make_call, if error occurs in rxrpc_kernel_send_data, it will call
afs_put_call twice, which will free the call. And the access of
call->state will trigger a use-after-free bug.

Signed-off-by: Zheng Wang <zyytlz.wz@....com>
---
 fs/afs/rxrpc.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index c62939e5ea1f..4871210c4b81 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -422,8 +422,7 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
 		call->rxcall = NULL;
 	}
 	if (call->async) {
-		if (cancel_work_sync(&call->async_work))
-			afs_put_call(call);
+		cancel_work_sync(&call->async_work);
 		afs_put_call(call);
 	}
 
-- 
2.25.1