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Date:   Sun, 22 Aug 2021 17:06:06 -0400
Message-Id: <1625bc89782bf83d9d8c7c63e8ffcb651ccb15fa.1629655338.git.olivier@trillion01.com>
In-Reply-To: <cover.1629655338.git.olivier@trillion01.com>
References: <cover.1629655338.git.olivier@trillion01.com>
From:   Olivier Langlois <olivier@trillion01.com>
To:     Jens Axboe <axboe@kernel.dk>,
        Pavel Begunkov <asml.silence@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH 3/3] coredump: cancel io_uring requests before dumping core
Precedence: bulk

The previous solution of ignoring the TIF_NOTIFY_SIGNAL bit while
dumping core is only working when the core dump is sent in a file.

When a pipe is used, pipe_write returns -ERESTARTSYS if signal_pending
which includes TIF_NOTIFY_SIGNAL is true.

A more robust solution is to make sure that io_uring will not set
TIF_NOTIFY_SIGNAL while the core dump is generated by cancelling all
the io_uring requests made by the current task before starting.

Fixes: 06af8679449d ("coredump: Limit what can interrupt coredumps")
Signed-off-by: Olivier Langlois <olivier@trillion01.com>
---
 fs/coredump.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/coredump.c b/fs/coredump.c
index 07afb5ddb1c4..9aceb4b3b40d 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -41,6 +41,7 @@
 #include <linux/fs.h>
 #include <linux/path.h>
 #include <linux/timekeeping.h>
+#include <linux/io_uring.h>
 
 #include <linux/uaccess.h>
 #include <asm/mmu_context.h>
@@ -625,6 +626,8 @@ void do_coredump(const kernel_siginfo_t *siginfo)
 		need_suid_safe = true;
 	}
 
+	io_uring_task_cancel();
+
 	retval = coredump_wait(siginfo->si_signo, &core_state);
 	if (retval < 0)
 		goto fail_creds;
-- 
2.32.0