From: Jens Axboe axboe@kernel.dk
commit a09c17240bdf2e9fa6d0591afa9448b59785f7d4 upstream.
A recent commit ensured that SQPOLL cannot be setup with a CPU that isn't in the current tasks cpuset, but it also dropped testing whether the CPU is valid in the first place. Without that, if a task passes in a CPU value that is too high, the following KASAN splat can get triggered:
BUG: KASAN: stack-out-of-bounds in io_sq_offload_create+0x858/0xaa4 Read of size 8 at addr ffff800089bc7b90 by task wq-aff.t/1391
CPU: 4 UID: 1000 PID: 1391 Comm: wq-aff.t Not tainted 6.11.0-rc7-00227-g371c468f4db6 #7080 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace.part.0+0xcc/0xe0 show_stack+0x14/0x1c dump_stack_lvl+0x58/0x74 print_report+0x16c/0x4c8 kasan_report+0x9c/0xe4 __asan_report_load8_noabort+0x1c/0x24 io_sq_offload_create+0x858/0xaa4 io_uring_setup+0x1394/0x17c4 __arm64_sys_io_uring_setup+0x6c/0x180 invoke_syscall+0x6c/0x260 el0_svc_common.constprop.0+0x158/0x224 do_el0_svc+0x3c/0x5c el0_svc+0x34/0x70 el0t_64_sync_handler+0x118/0x124 el0t_64_sync+0x168/0x16c
The buggy address belongs to stack of task wq-aff.t/1391 and is located at offset 48 in frame: io_sq_offload_create+0x0/0xaa4
This frame has 1 object: [32, 40) 'allowed_mask'
The buggy address belongs to the virtual mapping at [ffff800089bc0000, ffff800089bc9000) created by: kernel_clone+0x124/0x7e0
The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff0000d740af80 pfn:0x11740a memcg:ffff0000c2706f02 flags: 0xbffe00000000000(node=0|zone=2|lastcpupid=0x1fff) raw: 0bffe00000000000 0000000000000000 dead000000000122 0000000000000000 raw: ffff0000d740af80 0000000000000000 00000001ffffffff ffff0000c2706f02 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff800089bc7a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff800089bc7b00: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
ffff800089bc7b80: 00 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
^ ffff800089bc7c00: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 ffff800089bc7c80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f3
Reported-by: kernel test robot oliver.sang@intel.com Closes: https://lore.kernel.org/oe-lkp/202409161632.cbeeca0d-lkp@intel.com Fixes: f011c9cf04c0 ("io_uring/sqpoll: do not allow pinning outside of cpuset") Tested-by: Felix Moessbauer felix.moessbauer@siemens.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Felix Moessbauer felix.moessbauer@siemens.com --- io_uring/io_uring.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 6b6fd244233f8..a260852a0490c 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -8751,6 +8751,8 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx, int cpu = p->sq_thread_cpu;
ret = -EINVAL; + if (cpu >= nr_cpu_ids || !cpu_online(cpu)) + goto err_sqpoll; cpuset_cpus_allowed(current, &allowed_mask); if (!cpumask_test_cpu(cpu, &allowed_mask)) goto err_sqpoll;