| From | Ben Hutchings <> | Date | Sun, 03 Feb 2019 14:45:08 +0100 | Subject | [PATCH 3.16 277/305] aio: fix spectre gadget in lookup_ioctx |
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3.16.63-rc1 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.
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> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- fs/aio.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/fs/aio.c +++ b/fs/aio.c @@ -43,6 +43,7 @@ #include <asm/kmap_types.h> #include <asm/uaccess.h> +#include <linux/nospec.h> #include "internal.h" @@ -1022,6 +1023,7 @@ 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))
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