From c6a45ee7607de3a350008630f4369b1b5ac80884 Mon Sep 17 00:00:00 2001 From: Kevin Brodsky Date: Wed, 26 Nov 2025 12:48:35 +0000 Subject: [PATCH] ublk: prevent invalid access with DEBUG ublk_ch_uring_cmd_local() may jump to the out label before initialising the io pointer. This will cause trouble if DEBUG is defined, because the pr_devel() call dereferences io. Clang reports: drivers/block/ublk_drv.c:2403:6: error: variable 'io' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized] 2403 | if (tag >= ub->dev_info.queue_depth) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/block/ublk_drv.c:2492:32: note: uninitialized use occurs here 2492 | __func__, cmd_op, tag, ret, io->flags); | Fix this by initialising io to NULL and checking it before dereferencing it. Signed-off-by: Kevin Brodsky Fixes: 71f28f3136af ("ublk_drv: add io_uring based userspace block driver") Reviewed-by: Caleb Sander Mateos Signed-off-by: Jens Axboe --- drivers/block/ublk_drv.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 75f210523e52..09718a68137c 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -2301,7 +2301,7 @@ static int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd, u16 buf_idx = UBLK_INVALID_BUF_IDX; struct ublk_device *ub = cmd->file->private_data; struct ublk_queue *ubq; - struct ublk_io *io; + struct ublk_io *io = NULL; u32 cmd_op = cmd->cmd_op; u16 q_id = READ_ONCE(ub_src->q_id); u16 tag = READ_ONCE(ub_src->tag); @@ -2422,7 +2422,7 @@ static int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd, out: pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n", - __func__, cmd_op, tag, ret, io->flags); + __func__, cmd_op, tag, ret, io ? io->flags : 0); return ret; }