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ublk: prevent invalid access with DEBUG

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[ Upstream commit c6a45ee7607de3a350008630f4369b1b5ac80884 ]

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 <kevin.brodsky@arm.com>
Fixes: 71f28f3136 ("ublk_drv: add io_uring based userspace block driver")
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kevin Brodsky
2025-11-26 12:48:35 +00:00
committed by Greg Kroah-Hartman
parent 0a0a51092c
commit db5deba07f
1 changed files with 2 additions and 2 deletions
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4
drivers/block/ublk_drv.c
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@@ -1709,7 +1709,7 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
{
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;
unsigned tag = ub_cmd->tag;
int ret = -EINVAL;
@@ -1822,7 +1822,7 @@ static int __ublk_ch_uring_cmd(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;
}