4.9-stable review patch. If anyone has any objections, please let me know.
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From: John Garry john.garry@huawei.com
[ Upstream commit fae2a63737e5973f1426bc139935a0f42e232844 ]
Currently smatch warns of possible Spectre-V1 issue in ahci_led_store(): drivers/ata/libahci.c:1150 ahci_led_store() warn: potential spectre issue 'pp->em_priv' (local cap)
Userspace controls @pmp from following callchain: em_message->store() ->ata_scsi_em_message_store() -->ap->ops->em_store() --->ahci_led_store()
After the mask+shift @pmp is effectively an 8b value, which is used to index into an array of length 8, so sanitize the array index.
Signed-off-by: John Garry john.garry@huawei.com Signed-off-by: Tejun Heo tj@kernel.org
Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/ata/libahci.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/drivers/ata/libahci.c +++ b/drivers/ata/libahci.c @@ -35,6 +35,7 @@ #include <linux/kernel.h> #include <linux/gfp.h> #include <linux/module.h> +#include <linux/nospec.h> #include <linux/blkdev.h> #include <linux/delay.h> #include <linux/interrupt.h> @@ -1124,10 +1125,12 @@ static ssize_t ahci_led_store(struct ata
/* get the slot number from the message */ pmp = (state & EM_MSG_LED_PMP_SLOT) >> 8; - if (pmp < EM_MAX_SLOTS) + if (pmp < EM_MAX_SLOTS) { + pmp = array_index_nospec(pmp, EM_MAX_SLOTS); emp = &pp->em_priv[pmp]; - else + } else { return -EINVAL; + }
/* mask off the activity bits if we are in sw_activity * mode, user should turn off sw_activity before setting