This is a note to let you know that I've just added the patch titled

hwrng: core - Clean up RNG list when last hwrng is unregistered

to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: hwrng-core-clean-up-rng-list-when-last-hwrng-is-unregistered.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Thu Mar 22 14:03:40 CET 2018

From: Gary R Hook gary.hook@amd.com Date: Fri, 15 Dec 2017 13:55:59 -0600 Subject: hwrng: core - Clean up RNG list when last hwrng is unregistered

From: Gary R Hook gary.hook@amd.com

[ Upstream commit 0e4b52942b1c76f89e0dcb829f72e123d0678f54 ]

Commit 142a27f0a731 added support for a "best" RNG, and in doing so introduced a hang from rmmod/modprobe -r when the last RNG on the list was unloaded.

When the hwrng list is depleted, return the global variables to their original state and decrement all references to the object.

Fixes: 142a27f0a731 ("hwrng: core - Reset user selected rng by writing "" to rng_current") Signed-off-by: Gary R Hook gary.hook@amd.com Reviewed-by: PrasannaKumar Muralidharan prasannatsmkumar@gmail.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/char/hw_random/core.c | 4 ++++ 1 file changed, 4 insertions(+)

--- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -306,6 +306,10 @@ static int enable_best_rng(void) ret = ((new_rng == current_rng) ? 0 : set_current_rng(new_rng)); if (!ret) cur_rng_set_by_user = 0; + } else { + drop_current_rng(); + cur_rng_set_by_user = 0; + ret = 0; }

return ret;

Patches currently in stable-queue which might be from gary.hook@amd.com are

queue-4.15/hwrng-core-clean-up-rng-list-when-last-hwrng-is-unregistered.patch