4.4-stable review patch. If anyone has any objections, please let me know.
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From: Dan Carpenter dan.carpenter@oracle.com
commit 432798195bbce1f8cd33d1c0284d0538835e25fb upstream.
I was trying to solve a double free but I introduced a more serious NULL dereference bug. The problem is that if there is an IRQ which triggers immediately, then we need "info->uio_dev" but it's not set yet.
This patch puts the original initialization back to how it was and just sets info->uio_dev to NULL on the error path so it should solve both the Oops and the double free.
Fixes: f019f07ecf6a ("uio: potential double frees if __uio_register_device() fails") Reported-by: Mathias Thore Mathias.Thore@infinera.com Signed-off-by: Dan Carpenter dan.carpenter@oracle.com Cc: stable stable@vger.kernel.org Tested-by: Mathias Thore Mathias.Thore@infinera.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/uio/uio.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -842,6 +842,8 @@ int __uio_register_device(struct module if (ret) goto err_uio_dev_add_attributes;
+ info->uio_dev = idev; + if (info->irq && (info->irq != UIO_IRQ_CUSTOM)) { /* * Note that we deliberately don't use devm_request_irq @@ -853,11 +855,12 @@ int __uio_register_device(struct module */ ret = request_irq(info->irq, uio_interrupt, info->irq_flags, info->name, idev); - if (ret) + if (ret) { + info->uio_dev = NULL; goto err_request_irq; + } }
- info->uio_dev = idev; return 0;
err_request_irq: