| Message ID | 9ce0055a-709c-4ff1-b4d9-af6167c5de12@kernel.dk (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | io_uring/msg_ring: fix uninitialized use of target_req->flags | expand |
diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c index 29fa9285a33d..7fd9badcfaf8 100644 --- a/io_uring/msg_ring.c +++ b/io_uring/msg_ring.c @@ -110,10 +110,10 @@ static struct io_kiocb *io_msg_get_kiocb(struct io_ring_ctx *ctx) if (spin_trylock(&ctx->msg_lock)) { req = io_alloc_cache_get(&ctx->msg_cache); spin_unlock(&ctx->msg_lock); + if (req) + return req; } - if (req) - return req; - return kmem_cache_alloc(req_cachep, GFP_KERNEL | __GFP_NOWARN); + return kmem_cache_alloc(req_cachep, GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO); } static int io_msg_data_remote(struct io_kiocb *req)
io_uring/msg_ring: fix uninitialized use of target_req->flags syzbot reports that KMSAN complains that 'nr_tw' is an uninit-value with the following report: BUG: KMSAN: uninit-value in io_req_local_work_add io_uring/io_uring.c:1192 [inline] BUG: KMSAN: uninit-value in io_req_task_work_add_remote+0x588/0x5d0 io_uring/io_uring.c:1240 io_req_local_work_add io_uring/io_uring.c:1192 [inline] io_req_task_work_add_remote+0x588/0x5d0 io_uring/io_uring.c:1240 io_msg_remote_post io_uring/msg_ring.c:102 [inline] io_msg_data_remote io_uring/msg_ring.c:133 [inline] io_msg_ring_data io_uring/msg_ring.c:152 [inline] io_msg_ring+0x1c38/0x1ef0 io_uring/msg_ring.c:305 io_issue_sqe+0x383/0x22c0 io_uring/io_uring.c:1710 io_queue_sqe io_uring/io_uring.c:1924 [inline] io_submit_sqe io_uring/io_uring.c:2180 [inline] io_submit_sqes+0x1259/0x2f20 io_uring/io_uring.c:2295 __do_sys_io_uring_enter io_uring/io_uring.c:3205 [inline] __se_sys_io_uring_enter+0x40c/0x3ca0 io_uring/io_uring.c:3142 __x64_sys_io_uring_enter+0x11f/0x1a0 io_uring/io_uring.c:3142 x64_sys_call+0x2d82/0x3c10 arch/x86/include/generated/asm/syscalls_64.h:427 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f which is the following check: if (nr_tw < nr_wait) return; in io_req_local_work_add(). While nr_tw itself cannot be uninitialized, it does depend on req->flags, which off the msg ring issue path can indeed be uninitialized. Fix this by always clearing the allocated 'req' fully if we can't grab one from the cache itself. Fixes: 50cf5f3842af ("io_uring/msg_ring: add an alloc cache for io_kiocb entries") Reported-by: syzbot+82609b8937a4458106ca@syzkaller.appspotmail.com Link: https://lore.kernel.org/io-uring/000000000000fd3d8d061dfc0e4a@google.com/ Signed-off-by: Jens Axboe <axboe@kernel.dk> ---