Commit a538e3ff authored by Jeff Moyer's avatar Jeff Moyer Committed by Jens Axboe
Browse files

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.

Reported-by: default avatarMatthew Wilcox <>
Reported-by: default avatarDan Carpenter <>
Signed-off-by: default avatarJeff Moyer <>
Signed-off-by: default avatarJens Axboe <>
parent f55adad6
...@@ -45,6 +45,7 @@ ...@@ -45,6 +45,7 @@
#include <asm/kmap_types.h> #include <asm/kmap_types.h>
#include <linux/uaccess.h> #include <linux/uaccess.h>
#include <linux/nospec.h>
#include "internal.h" #include "internal.h"
...@@ -1038,6 +1039,7 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) ...@@ -1038,6 +1039,7 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id)
if (!table || id >= table->nr) if (!table || id >= table->nr)
goto out; goto out;
id = array_index_nospec(id, table->nr);
ctx = rcu_dereference(table->table[id]); ctx = rcu_dereference(table->table[id]);
if (ctx && ctx->user_id == ctx_id) { if (ctx && ctx->user_id == ctx_id) {
if (percpu_ref_tryget_live(&ctx->users)) if (percpu_ref_tryget_live(&ctx->users))
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