6.11-stable review patch. If anyone has any objections, please let me know.
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From: Josh Poimboeuf jpoimboe@kernel.org
[ Upstream commit b0bf1afde7c34698cf61422fa8ee60e690dc25c3 ]
The barrier_nospec() after the array bounds check is overkill and painfully slow for arches which implement it.
Furthermore, most arches don't implement it, so they remain exposed to Spectre v1 (which can affect pretty much any CPU with branch prediction).
Instead, clamp the user pointer to a valid range so it's guaranteed to be a valid array index even when the bounds check mispredicts.
Fixes: 8270cb10c068 ("cdrom: Fix spectre-v1 gadget") Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Link: https://lore.kernel.org/r/1d86f4d9d8fba68e5ca64cdeac2451b95a8bf872.172920293... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/cdrom/cdrom.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c index 9b0f37d4b9d49..6a99a459b80b2 100644 --- a/drivers/cdrom/cdrom.c +++ b/drivers/cdrom/cdrom.c @@ -2313,7 +2313,7 @@ static int cdrom_ioctl_media_changed(struct cdrom_device_info *cdi, return -EINVAL;
/* Prevent arg from speculatively bypassing the length check */ - barrier_nospec(); + arg = array_index_nospec(arg, cdi->capacity);
info = kmalloc(sizeof(*info), GFP_KERNEL); if (!info)