On 9/16/24 2:35 AM, kerne test robot wrote:
> [ 155.627997][ T6168] BUG: KASAN: slab-out-of-bounds in io_sq_offload_create (arch/x86/include/asm/bitops.h:227 arch/x86/include/asm/bitops.h:239 include/asm-generic/bitops/instrumented-non-atomic.h:142 include/linux/cpumask.h:562 io_uring/sqpoll.c:469)
> [ 155.628787][ T6168] Read of size 8 at addr ffff888138ecf948 by task trinity-c3/6168
> [ 155.629542][ T6168]
> [ 155.629806][ T6168] CPU: 1 UID: 4294967291 PID: 6168 Comm: trinity-c3 Not tainted 6.11.0-rc5-00027-gf011c9cf04c0 #1 074b2dc9794d1910767b5e24d1a9cb7061a66647
> [ 155.631255][ T6168] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> [ 155.632276][ T6168] Call Trace:
> [ 155.632627][ T6168] <TASK>
> [ 155.632952][ T6168] dump_stack_lvl (lib/dump_stack.c:122)
> [ 155.633418][ T6168] print_address_description+0x51/0x3a0
> [ 155.634147][ T6168] ? io_sq_offload_create (arch/x86/include/asm/bitops.h:227 arch/x86/include/asm/bitops.h:239 include/asm-generic/bitops/instrumented-non-atomic.h:142 include/linux/cpumask.h:562 io_uring/sqpoll.c:469)
> [ 155.634671][ T6168] print_report (mm/kasan/report.c:489)
> [ 155.635119][ T6168] ? lock_acquired (include/trace/events/lock.h:85 kernel/locking/lockdep.c:6039)
> [ 155.635596][ T6168] ? kasan_addr_to_slab (include/linux/mm.h:1283 mm/kasan/../slab.h:206 mm/kasan/common.c:38)
> [ 155.636243][ T6168] ? io_sq_offload_create (arch/x86/include/asm/bitops.h:227 arch/x86/include/asm/bitops.h:239 include/asm-generic/bitops/instrumented-non-atomic.h:142 include/linux/cpumask.h:562 io_uring/sqpoll.c:469)
> [ 155.636890][ T6168] kasan_report (mm/kasan/report.c:603)
> [ 155.637320][ T6168] ? io_sq_offload_create (arch/x86/include/asm/bitops.h:227 arch/x86/include/asm/bitops.h:239 include/asm-generic/bitops/instrumented-non-atomic.h:142 include/linux/cpumask.h:562 io_uring/sqpoll.c:469)
> [ 155.637873][ T6168] kasan_check_range (mm/kasan/generic.c:183 mm/kasan/generic.c:189)
> [ 155.638384][ T6168] io_sq_offload_create (arch/x86/include/asm/bitops.h:227 arch/x86/include/asm/bitops.h:239 include/asm-generic/bitops/instrumented-non-atomic.h:142 include/linux/cpumask.h:562 io_uring/sqpoll.c:469)
> [ 155.638921][ T6168] ? __pfx_io_sq_offload_create (io_uring/sqpoll.c:413)
> [ 155.639501][ T6168] ? __lock_acquire (kernel/locking/lockdep.c:5142)
> [ 155.640040][ T6168] ? io_pages_map (include/linux/gfp.h:269 include/linux/gfp.h:296 include/linux/gfp.h:313 io_uring/memmap.c:28 io_uring/memmap.c:72)
> [ 155.640495][ T6168] ? io_allocate_scq_urings (io_uring/io_uring.c:3441)
> [ 155.641079][ T6168] io_uring_create (io_uring/io_uring.c:3606)
> [ 155.641591][ T6168] io_uring_setup (io_uring/io_uring.c:3715)
> [ 155.642185][ T6168] ? __pfx_io_uring_setup (io_uring/io_uring.c:3693)
> [ 155.642698][ T6168] ? do_int80_emulation (arch/x86/include/asm/irqflags.h:42 arch/x86/include/asm/irqflags.h:97 arch/x86/entry/common.c:251)
> [ 155.643206][ T6168] do_int80_emulation (arch/x86/entry/common.c:165 arch/x86/entry/common.c:253)
> [ 155.643675][ T6168] asm_int80_emulation (arch/x86/include/asm/idtentry.h:626)
The fix for the cpusets dropped checking if the value was sane to begin
with... I've fixed it up with the patch below.
commit 827e3ea024a4facf1d6c8969ae95de939890039e
Author: Jens Axboe <axboe@xxxxxxxxx>
Date: Mon Sep 16 02:58:06 2024 -0600
io_uring/sqpoll: retain test for whether the CPU is valid
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@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-lkp/202409161632.cbeeca0d-lkp@xxxxxxxxx
Fixes: f011c9cf04c0 ("io_uring/sqpoll: do not allow pinning outside of cpuset")
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c
index 272df9d00f45..7adfcf6818ff 100644
--- a/io_uring/sqpoll.c
+++ b/io_uring/sqpoll.c
@@ -465,6 +465,8 @@ __cold 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;
--
Jens Axboe
