From a538e3ff9dabcdf6c3f477a373c629213d1c3066 Mon Sep 17 00:00:00 2001 From: Jeff Moyer Date: Tue, 11 Dec 2018 12:37:49 -0500 Subject: aio: fix spectre gadget in lookup_ioctx Matthew pointed out that the ioctx_table is susceptible to spectre v1, because the index can be controlled by an attacker. The below patch should mitigate the attack for all of the aio system calls. Cc: stable@vger.kernel.org Reported-by: Matthew Wilcox Reported-by: Dan Carpenter Signed-off-by: Jeff Moyer Signed-off-by: Jens Axboe --- fs/aio.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/aio.c') diff --git a/fs/aio.c b/fs/aio.c index 301e6314183b..20c07664314a 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -45,6 +45,7 @@ #include #include +#include #include "internal.h" @@ -1038,6 +1039,7 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) if (!table || id >= table->nr) goto out; + id = array_index_nospec(id, table->nr); ctx = rcu_dereference(table->table[id]); if (ctx && ctx->user_id == ctx_id) { if (percpu_ref_tryget_live(&ctx->users)) -- cgit v1.2.3