4.4-stable review patch. If anyone has any objections, please let me know.
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From: Jeff Moyer jmoyer@redhat.com
commit a538e3ff9dabcdf6c3f477a373c629213d1c3066 upstream.
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 willy@infradead.org Reported-by: Dan Carpenter dan.carpenter@oracle.com Signed-off-by: Jeff Moyer jmoyer@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/aio.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/fs/aio.c +++ b/fs/aio.c @@ -40,6 +40,7 @@ #include <linux/ramfs.h> #include <linux/percpu-refcount.h> #include <linux/mount.h> +#include <linux/nospec.h>
#include <asm/kmap_types.h> #include <asm/uaccess.h> @@ -1063,6 +1064,7 @@ static struct kioctx *lookup_ioctx(unsig 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))