diff options
| author | Jens Axboe <axboe@kernel.dk> | 2023-10-21 12:30:29 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-11-28 16:56:36 +0000 |
| commit | 3d7912710e5e187217313fea5c145881cfeaf952 (patch) | |
| tree | 80e05e835aa15d55c1679ac0ae3d045cec015ec8 | |
| parent | 595b051c83a1374b1d53ab44de1c27ac60b95979 (diff) | |
io_uring/fdinfo: lock SQ thread while retrieving thread cpu/pid
commit 7644b1a1c9a7ae8ab99175989bfc8676055edb46 upstream.
We could race with SQ thread exit, and if we do, we'll hit a NULL pointer
dereference when the thread is cleared. Grab the SQPOLL data lock before
attempting to get the task cpu and pid for fdinfo, this ensures we have a
stable view of it.
Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218032
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: He Gao <hegao@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | io_uring/io_uring.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index d00bedfdadbb..e26292d8b845 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -10411,7 +10411,7 @@ static int io_uring_show_cred(struct seq_file *m, unsigned int id, static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m) { - struct io_sq_data *sq = NULL; + int sq_pid = -1, sq_cpu = -1; bool has_lock; int i; @@ -10424,13 +10424,19 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m) has_lock = mutex_trylock(&ctx->uring_lock); if (has_lock && (ctx->flags & IORING_SETUP_SQPOLL)) { - sq = ctx->sq_data; - if (!sq->thread) - sq = NULL; + struct io_sq_data *sq = ctx->sq_data; + + if (mutex_trylock(&sq->lock)) { + if (sq->thread) { + sq_pid = task_pid_nr(sq->thread); + sq_cpu = task_cpu(sq->thread); + } + mutex_unlock(&sq->lock); + } } - seq_printf(m, "SqThread:\t%d\n", sq ? task_pid_nr(sq->thread) : -1); - seq_printf(m, "SqThreadCpu:\t%d\n", sq ? task_cpu(sq->thread) : -1); + seq_printf(m, "SqThread:\t%d\n", sq_pid); + seq_printf(m, "SqThreadCpu:\t%d\n", sq_cpu); seq_printf(m, "UserFiles:\t%u\n", ctx->nr_user_files); for (i = 0; has_lock && i < ctx->nr_user_files; i++) { struct file *f = io_file_from_index(ctx, i); |