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authorDylan Yudaken <dylany@fb.com>2022-02-22 19:17:51 +0300
committerJens Axboe <axboe@kernel.dk>2022-02-22 19:57:32 +0300
commit80912cef18f16f8fe59d1fb9548d4364342be360 (patch)
treede6b869f7af34d8f31912d2f7c1b3326938fba1d /fs
parent228339662b398a59b3560cd571deb8b25b253c7e (diff)
downloadlinux-80912cef18f16f8fe59d1fb9548d4364342be360.tar.xz
io_uring: disallow modification of rsrc_data during quiesce
io_rsrc_ref_quiesce will unlock the uring while it waits for references to the io_rsrc_data to be killed. There are other places to the data that might add references to data via calls to io_rsrc_node_switch. There is a race condition where this reference can be added after the completion has been signalled. At this point the io_rsrc_ref_quiesce call will wake up and relock the uring, assuming the data is unused and can be freed - although it is actually being used. To fix this check in io_rsrc_ref_quiesce if a resource has been revived. Reported-by: syzbot+ca8bf833622a1662745b@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Dylan Yudaken <dylany@fb.com> Link: https://lore.kernel.org/r/20220222161751.995746-1-dylany@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
-rw-r--r--fs/io_uring.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 928446fe1319..4715980e9015 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7926,7 +7926,15 @@ static __cold int io_rsrc_ref_quiesce(struct io_rsrc_data *data,
ret = wait_for_completion_interruptible(&data->done);
if (!ret) {
mutex_lock(&ctx->uring_lock);
- break;
+ if (atomic_read(&data->refs) > 0) {
+ /*
+ * it has been revived by another thread while
+ * we were unlocked
+ */
+ mutex_unlock(&ctx->uring_lock);
+ } else {
+ break;
+ }
}
atomic_inc(&data->refs);