This is a note to let you know that I've just added the patch titled usb: gadget: storage: Fix Spectre v1 vulnerability to the 4.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-gadget-storage-fix-spectre-v1-vulnerability.patch and it can be found in the queue-4.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 9ae24af3669111d418242caec8dd4ebd9ba26860 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx> Date: Tue, 16 Oct 2018 12:16:45 +0200 Subject: usb: gadget: storage: Fix Spectre v1 vulnerability From: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> commit 9ae24af3669111d418242caec8dd4ebd9ba26860 upstream. num can be indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: drivers/usb/gadget/function/f_mass_storage.c:3177 fsg_lun_make() warn: potential spectre issue 'fsg_opts->common->luns' [r] (local cap) Fix this by sanitizing num before using it to index fsg_opts->common->luns Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> Acked-by: Felipe Balbi <felipe.balbi@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/gadget/function/f_mass_storage.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/usb/gadget/function/f_mass_storage.c +++ b/drivers/usb/gadget/function/f_mass_storage.c @@ -222,6 +222,8 @@ #include <linux/usb/gadget.h> #include <linux/usb/composite.h> +#include <linux/nospec.h> + #include "configfs.h" @@ -3171,6 +3173,7 @@ static struct config_group *fsg_lun_make fsg_opts = to_fsg_opts(&group->cg_item); if (num >= FSG_MAX_LUNS) return ERR_PTR(-ERANGE); + num = array_index_nospec(num, FSG_MAX_LUNS); mutex_lock(&fsg_opts->lock); if (fsg_opts->refcnt || fsg_opts->common->luns[num]) { Patches currently in stable-queue which might be from gustavo@xxxxxxxxxxxxxx are queue-4.18/ptp-fix-spectre-v1-vulnerability.patch queue-4.18/rdma-ucma-fix-spectre-v1-vulnerability.patch queue-4.18/usb-gadget-storage-fix-spectre-v1-vulnerability.patch queue-4.18/ib-ucm-fix-spectre-v1-vulnerability.patch