On Sat, Aug 29, 2020 at 5:12 PM Colin Ian King <colin.king@xxxxxxxxxxxxx> wrote: > > On 27/08/2020 14:39, Leon Romanovsky wrote: > > From: Leon Romanovsky <leonro@xxxxxxxxxx> > > > > The kernel compiled with GCC 10.2.1 and KASAN together with GCOV enabled > > produces the following splats while reloading modules. > > > > First splat [1] is generated due to the situation that gcov_info can be both > > user and kernel pointer, the memcpy() during kmemdup() causes to this. > > As a possible solution copy fields manually. > > > > Second splat [2] is seen because n_function provided by GCC through > > __gcov_init() is ridiculously high, in my case it was 2698213824. > > IMHO it means that this field is not initialized, but I'm not sure. > > > > [1] > > ================================================================== > > BUG: KASAN: global-out-of-bounds in kmemdup+0x43/0x70 > > Read of size 120 at addr ffffffffa0d2c780 by task modprobe/296 > > > > CPU: 0 PID: 296 Comm: modprobe Not tainted 5.9.0-rc1+ #1860 > > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04 /01/2014 > > Call Trace: > > ? dump_stack+0x128/0x1af > > ? print_address_description.constprop.0+0x2c/0x3f0 > > ? _raw_spin_lock_irqsave+0x34/0xa0 > > ? __kasan_check_read+0x1d/0x30 > > ? kmemdup+0x43/0x70 > > ? kmemdup+0x43/0x70 > > ? gcov_info_dup+0x2d/0x730 > > ? __kasan_check_write+0x20/0x30 > > ? __mutex_unlock_slowpath+0x10d/0x740 > > ? gcov_event+0x88d/0xd30 > > ? gcov_module_notifier+0xe9/0x100 > > ? notifier_call_chain+0xeb/0x170 > > ? blocking_notifier_call_chain+0x75/0xc0 > > ? __x64_sys_delete_module+0x326/0x5a0 > > ? do_init_module+0x810/0x810 > > ? syscall_enter_from_user_mode+0x40/0x420 > > ? trace_hardirqs_on+0x45/0xb0 > > ? syscall_enter_from_user_mode+0x40/0x420 > > ? do_syscall_64+0x45/0x70 > > ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > > > The buggy address belongs to the variable: > > __gcov_.uverbs_attr_get_obj+0x60/0xfffffffffff778e0 [mlx5_ib] > > > > Memory state around the buggy address: > > ffffffffa0d2c680: 00 f9 f9 f9 f9 f9 f9 f9 00 00 00 00 00 f9 f9 f9 > > ffffffffa0d2c700: f9 f9 f9 f9 00 00 00 00 00 f9 f9 f9 f9 f9 f9 f9 > > >ffffffffa0d2c780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f9 f9 > > ^ > > ffffffffa0d2c800: f9 f9 f9 f9 00 00 00 00 00 f9 f9 f9 f9 f9 f9 f9 > > ffffffffa0d2c880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > ================================================================== > > Disabling lock debugging due to kernel taint > > gcov: could not save data for '/home/leonro/src/kernel/drivers/infiniband/hw/mlx5/std_types.gcda' (out o > > f memory) > > > > [2] > > Colin has similar error [3]. > > > > ------------[ cut here ]------------ > > WARNING: CPU: 0 PID: 296 at mm/page_alloc.c:4859 __alloc_pages_nodemask+0x670/0x3190 > > Modules linked in: mlx5_ib(-) mlx5_core mlxfw ptp ib_ipoib pps_core rdma_ucm rdma_cm iw_cm ib_cm ib_umad ib_uverbs ib_core > > CPU: 0 PID: 296 Comm: modprobe Tainted: G B 5.9.0-rc1+ #1860 > > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04 /01/2014 > > RIP: 0010:__alloc_pages_nodemask+0x670/0x3190 > > Code: e9 af fc ff ff 48 83 05 fd 28 90 05 01 81 e7 00 20 00 00 48 c7 44 24 28 00 00 00 00 0f 85 fb fd ff ff 48 83 05 f0 28 90 05 01 <0f> 0b 48 83 05 ee 28 90 05 01 48 83 05 ee 28 90 05 01 e9 dc fd ff > > RSP: 0018:ffff88805f7ffa28 EFLAGS: 00010202 > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 1ffff1100befff5e > > RDX: 0000000000000000 RSI: 0000000000000017 RDI: 0000000000000000 > > RBP: 000000050695a900 R08: ffff888060fc7900 R09: ffff888060fc793b > > R10: ffffed100c1f8f27 R11: ffffed100c1f8f28 R12: 0000000000040dc0 > > R13: 000000050695a900 R14: 0000000000000017 R15: 0000000000000001 > > FS: 00007f521f695740(0000) GS:ffff88806ce00000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 00007f31b013f000 CR3: 000000006637e001 CR4: 0000000000370eb0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Call Trace: > > ? __kmalloc_track_caller+0x17a/0x570 > > ? gcov_info_dup+0xfe/0x730 > > ? gcov_event+0x88d/0xd30 > > ? gcov_module_notifier+0xe9/0x100 > > ? blocking_notifier_call_chain+0x75/0xc0 > > ? __x64_sys_delete_module+0x326/0x5a0 > > ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > ? mark_lock+0xba0/0xba0 > > ? mark_lock+0xba0/0xba0 > > ? notifier_call_chain+0xeb/0x170 > > ? blocking_notifier_call_chain+0x75/0xc0 > > ? __x64_sys_delete_module+0x326/0x5a0 > > ? do_syscall_64+0x45/0x70 > > ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > ? warn_alloc+0x130/0x130 > > ? lock_acquire+0x1f2/0xa30 > > ? fs_reclaim_acquire+0x1f/0x70 > > ? fs_reclaim_release+0x1f/0x50 > > ? __kasan_check_read+0x1d/0x30 > > ? reacquire_held_locks+0x420/0x420 > > ? reacquire_held_locks+0x420/0x420 > > kmalloc_order+0x3f/0xc0 > > kmalloc_order_trace+0x24/0x220 > > __kmalloc+0x41b/0x5a0 > > ? gcov_info_dup+0xfe/0x730 > > ? memcpy+0x73/0xa0 > > gcov_info_dup+0x176/0x730 > > gcov_event+0x88d/0xd30 > > gcov_module_notifier+0xe9/0x100 > > notifier_call_chain+0xeb/0x170 > > blocking_notifier_call_chain+0x75/0xc0 > > __x64_sys_delete_module+0x326/0x5a0 > > ? do_init_module+0x810/0x810 > > ? syscall_enter_from_user_mode+0x40/0x420 > > ? trace_hardirqs_on+0x45/0xb0 > > ? syscall_enter_from_user_mode+0x40/0x420 > > do_syscall_64+0x45/0x70 > > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > RIP: 0033:0x7f521f7c531b > > Code: 73 01 c3 48 8b 0d 7d 0b 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 4d 0b 0c 00 f7 d8 64 89 01 48 > > RSP: 002b:00007ffe1bd4af48 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0 > > RAX: ffffffffffffffda RBX: 0000561a3eae0910 RCX: 00007f521f7c531b > > RDX: 0000000000000000 RSI: 0000000000000800 RDI: 0000561a3eae0978 > > RBP: 0000561a3eae0910 R08: 1999999999999999 R09: 0000000000000000 > > R10: 00007f521f839ac0 R11: 0000000000000206 R12: 0000000000000000 > > R13: 0000561a3eae0978 R14: 0000000000000000 R15: 0000561a3eae84d0 > > irq event stamp: 326464 > > hardirqs last enabled at (326463): [<ffffffff832ecdde>] _raw_spin_unlock_irqrestore+0x8e/0xb0 > > hardirqs last disabled at (326464): [<ffffffff832ec994>] _raw_spin_lock_irqsave+0x34/0xa0 > > hardirqs last disabled at (326464): [<ffffffff832ec994>] _raw_spin_lock_irqsave+0x34/0xa0 > > softirqs last enabled at (320794): [<ffffffff83600931>] __do_softirq+0x931/0xbc4 > > softirqs last disabled at (320789): [<ffffffff83400f2f>] asm_call_on_stack+0xf/0x20 > > ---[ end trace 065ea9cc2ba144a6 ]--- > > > > [3] https://bugzilla.kernel.org/show_bug.cgi?id=208885#c1 > > Cc: Colin Ian King <colin.king@xxxxxxxxxxxxx> > > Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx> > > --- > > I have a strong feeling that this solution is not correct, but don't > > know how to do it right. The problem exists and reproducable in seconds. > > --- > > kernel/gcov/gcc_4_7.c | 19 +++++++++++-------- > > 1 file changed, 11 insertions(+), 8 deletions(-) > > > > diff --git a/kernel/gcov/gcc_4_7.c b/kernel/gcov/gcc_4_7.c > > index 908fdf5098c3..357ef839cdd3 100644 > > --- a/kernel/gcov/gcc_4_7.c > > +++ b/kernel/gcov/gcc_4_7.c > > @@ -275,20 +275,23 @@ struct gcov_info *gcov_info_dup(struct gcov_info *info) > > size_t fi_size; /* function info size */ > > size_t cv_size; /* counter values size */ > > > > - dup = kmemdup(info, sizeof(*dup), GFP_KERNEL); > > + dup = kzalloc(sizeof(*dup), GFP_KERNEL); > > if (!dup) > > return NULL; > > > > - dup->next = NULL; > > - dup->filename = NULL; > > - dup->functions = NULL; > > + dup->version = info->version; > > + dup->stamp = info->stamp; > > + for (fi_idx = 0; i < GCOV_COUNTERS; i++) > > This loop refers to i as a counter but it's not declared. Thanks, I wrote it above. https://lore.kernel.org/lkml/20200827151333.GB2909436@unreal The thing is that I would expect to hear any feedback if this GCC bug or not and how to solve it. We tried to GCC 9 and gcov worked there. Thanks
