From 308e8a922c8aca66903e3e0f73fabb1eb4e535c0 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Sun, 3 Jun 2018 22:06:14 +0200 Subject: [PATCH] 3.18-stable patches added patches: fix-io_destroy-aio_complete-race.patch --- .../fix-io_destroy-aio_complete-race.patch | 42 +++++++++++++++++++ queue-3.18/series | 1 + 2 files changed, 43 insertions(+) create mode 100644 queue-3.18/fix-io_destroy-aio_complete-race.patch diff --git a/queue-3.18/fix-io_destroy-aio_complete-race.patch b/queue-3.18/fix-io_destroy-aio_complete-race.patch new file mode 100644 index 00000000000..442e8d4df7f --- /dev/null +++ b/queue-3.18/fix-io_destroy-aio_complete-race.patch @@ -0,0 +1,42 @@ +From 4faa99965e027cc057c5145ce45fa772caa04e8d Mon Sep 17 00:00:00 2001 +From: Al Viro +Date: Wed, 23 May 2018 22:53:22 -0400 +Subject: fix io_destroy()/aio_complete() race + +From: Al Viro + +commit 4faa99965e027cc057c5145ce45fa772caa04e8d upstream. + +If io_destroy() gets to cancelling everything that can be cancelled and +gets to kiocb_cancel() calling the function driver has left in ->ki_cancel, +it becomes vulnerable to a race with IO completion. At that point req +is already taken off the list and aio_complete() does *NOT* spin until +we (in free_ioctx_users()) releases ->ctx_lock. As the result, it proceeds +to kiocb_free(), freing req just it gets passed to ->ki_cancel(). + +Fix is simple - remove from the list after the call of kiocb_cancel(). All +instances of ->ki_cancel() already have to cope with the being called with +iocb still on list - that's what happens in io_cancel(2). + +Cc: stable@kernel.org +Fixes: 0460fef2a921 "aio: use cancellation list lazily" +Signed-off-by: Al Viro +Signed-off-by: Greg Kroah-Hartman + +--- + fs/aio.c | 3 +-- + 1 file changed, 1 insertion(+), 2 deletions(-) + +--- a/fs/aio.c ++++ b/fs/aio.c +@@ -560,9 +560,8 @@ static void free_ioctx_users(struct perc + while (!list_empty(&ctx->active_reqs)) { + req = list_first_entry(&ctx->active_reqs, + struct kiocb, ki_list); +- +- list_del_init(&req->ki_list); + kiocb_cancel(req); ++ list_del_init(&req->ki_list); + } + + spin_unlock_irq(&ctx->ctx_lock); diff --git a/queue-3.18/series b/queue-3.18/series index 95b52e6f49b..202f954d01f 100644 --- a/queue-3.18/series +++ b/queue-3.18/series @@ -4,3 +4,4 @@ cfg80211-further-limit-wiphy-names-to-64-bytes.patch tcp-avoid-integer-overflows-in-tcp_rcv_space_adjust.patch mips-ptrace-fix-ptrace_peekusr-requests-for-64-bit-fgrs.patch drm-i915-disable-lvds-on-radiant-p845.patch +fix-io_destroy-aio_complete-race.patch -- 2.47.3