From: Yu Kuai yukuai3@huawei.com
mainline inclusion from mainline-v6.2-rc1 commit 077a4033541fc96fb0a955985aab7d1f353da831 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6B4N7 CVE: NA
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After creating a dm device, then user can reload such dm with itself, and dead loop will be triggered because dm keep looking up to itself.
Test procedures:
1) dmsetup create test --table "xxx sda", assume dm-0 is created 2) dmsetup suspend test 3) dmsetup reload test --table "xxx dm-0" 4) dmsetup resume test
Test result:
BUG: TASK stack guard page was hit at 00000000736a261f (stack is 000000008d12c88d..00000000c8dd82d5) stack guard page: 0000 [#1] PREEMPT SMP CPU: 29 PID: 946 Comm: systemd-udevd Not tainted 6.1.0-rc3-next-20221101-00006-g17640ca3b0ee #1295 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014 RIP: 0010:dm_prepare_ioctl+0xf/0x1e0 Code: da 48 83 05 4a 7c 99 0b 01 41 89 c4 eb cd e8 b8 1f 40 00 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 41 57 48 83 05 a1 5a 99 0b 01 <41> 56 49 89 d6 41 55 4c 8d af 90 02 00 00 9 RSP: 0018:ffffc90002090000 EFLAGS: 00010206 RAX: ffff8881049d6800 RBX: ffff88817e589000 RCX: 0000000000000000 RDX: ffffc90002090010 RSI: ffffc9000209001c RDI: ffff88817e589000 RBP: 00000000484a101d R08: 0000000000000000 R09: 0000000000000007 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000005331 R13: 0000000000005331 R14: 0000000000000000 R15: 0000000000000000 FS: 00007fddf9609200(0000) GS:ffff889fbfd40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffc9000208fff8 CR3: 0000000179043000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> dm_blk_ioctl+0x50/0x1c0 ? dm_prepare_ioctl+0xe0/0x1e0 dm_blk_ioctl+0x88/0x1c0 dm_blk_ioctl+0x88/0x1c0 ......(a lot of same lines) dm_blk_ioctl+0x88/0x1c0 dm_blk_ioctl+0x88/0x1c0 blkdev_ioctl+0x184/0x3e0 __x64_sys_ioctl+0xa3/0x110 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fddf7306577 Code: b3 66 90 48 8b 05 11 89 2c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e1 88 8 RSP: 002b:00007ffd0b2ec318 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00005634ef478320 RCX: 00007fddf7306577 RDX: 0000000000000000 RSI: 0000000000005331 RDI: 0000000000000007 RBP: 0000000000000007 R08: 00005634ef4843e0 R09: 0000000000000080 R10: 00007fddf75cfb38 R11: 0000000000000246 R12: 00000000030d4000 R13: 0000000000000000 R14: 0000000000000000 R15: 00005634ef48b800 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:dm_prepare_ioctl+0xf/0x1e0 Code: da 48 83 05 4a 7c 99 0b 01 41 89 c4 eb cd e8 b8 1f 40 00 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 41 57 48 83 05 a1 5a 99 0b 01 <41> 56 49 89 d6 41 55 4c 8d af 90 02 00 00 9 RSP: 0018:ffffc90002090000 EFLAGS: 00010206 RAX: ffff8881049d6800 RBX: ffff88817e589000 RCX: 0000000000000000 RDX: ffffc90002090010 RSI: ffffc9000209001c RDI: ffff88817e589000 RBP: 00000000484a101d R08: 0000000000000000 R09: 0000000000000007 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000005331 R13: 0000000000005331 R14: 0000000000000000 R15: 0000000000000000 FS: 00007fddf9609200(0000) GS:ffff889fbfd40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffc9000208fff8 CR3: 0000000179043000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Kernel panic - not syncing: Fatal exception in interrupt Kernel Offset: disabled ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
Fix the problem by forbidding a disk to create link to itself.
Signed-off-by: Yu Kuai yukuai3@huawei.com Reviewed-by: Christoph Hellwig hch@lst.de Link: https://lore.kernel.org/r/20221115141054.1051801-11-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Li Lingfeng lilingfeng3@huawei.com Reviewed-by: Yang Erkun yangerkun@huawei.com Reviewed-by: Zhang Yi yi.zhang@huawei.com Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com --- fs/block_dev.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/fs/block_dev.c b/fs/block_dev.c index 2680092c022d..6ba91b97753f 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1305,6 +1305,8 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) struct bd_holder_disk *holder; int ret = 0;
+ if (bdev->bd_disk == disk) + return -EINVAL; /* * bdev could be deleted beneath us which would implicitly destroy * the holder directory. Hold on to it.
From: "Steven Rostedt (Google)" rostedt@goodmis.org
stable inclusion from stable-v4.19.262 commit 7e642bd051706d1174fbeb6ec0da8a1fc2189264 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6CE9I CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit a0fcaaed0c46cf9399d3a2d6e0c87ddb3df0e044 upstream.
The ring buffer is broken up into sub buffers (currently of page size). Each sub buffer has a pointer to its "tail" (the last event written to the sub buffer). When a new event is requested, the tail is locally incremented to cover the size of the new event. This is done in a way that there is no need for locking.
If the tail goes past the end of the sub buffer, the process of moving to the next sub buffer takes place. After setting the current sub buffer to the next one, the previous one that had the tail go passed the end of the sub buffer needs to be reset back to the original tail location (before the new event was requested) and the rest of the sub buffer needs to be "padded".
The race happens when a reader takes control of the sub buffer. As readers do a "swap" of sub buffers from the ring buffer to get exclusive access to the sub buffer, it replaces the "head" sub buffer with an empty sub buffer that goes back into the writable portion of the ring buffer. This swap can happen as soon as the writer moves to the next sub buffer and before it updates the last sub buffer with padding.
Because the sub buffer can be released to the reader while the writer is still updating the padding, it is possible for the reader to see the event that goes past the end of the sub buffer. This can cause obvious issues.
To fix this, add a few memory barriers so that the reader definitely sees the updates to the sub buffer, and also waits until the writer has put back the "tail" of the sub buffer back to the last event that was written on it.
To be paranoid, it will only spin for 1 second, otherwise it will warn and shutdown the ring buffer code. 1 second should be enough as the writer does have preemption disabled. If the writer doesn't move within 1 second (with preemption disabled) something is horribly wrong. No interrupt should last 1 second!
Link: https://lore.kernel.org/all/20220830120854.7545-1-jiazi.li@transsion.com/ Link: https://bugzilla.kernel.org/show_bug.cgi?id=216369 Link: https://lkml.kernel.org/r/20220929104909.0650a36c@gandalf.local.home
Cc: Ingo Molnar mingo@kernel.org Cc: Andrew Morton akpm@linux-foundation.org Cc: stable@vger.kernel.org Fixes: c7b0930857e22 ("ring-buffer: prevent adding write in discarded area") Reported-by: Jiazi.Li jiazi.li@transsion.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Yejian zhengyejian1@huawei.com Reviewed-by: Yang Jihong yangjihong1@huawei.com Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com --- kernel/trace/ring_buffer.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 599a9cf12772..a9b32f620fb0 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2156,6 +2156,9 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, /* Mark the rest of the page with padding */ rb_event_set_padding(event);
+ /* Make sure the padding is visible before the write update */ + smp_wmb(); + /* Set the write back to the previous setting */ local_sub(length, &tail_page->write); return; @@ -2167,6 +2170,9 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, /* time delta must be non zero */ event->time_delta = 1;
+ /* Make sure the padding is visible before the tail_page->write update */ + smp_wmb(); + /* Set write to end of buffer */ length = (tail + length) - BUF_PAGE_SIZE; local_sub(length, &tail_page->write); @@ -3812,6 +3818,33 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) arch_spin_unlock(&cpu_buffer->lock); local_irq_restore(flags);
+ /* + * The writer has preempt disable, wait for it. But not forever + * Although, 1 second is pretty much "forever" + */ +#define USECS_WAIT 1000000 + for (nr_loops = 0; nr_loops < USECS_WAIT; nr_loops++) { + /* If the write is past the end of page, a writer is still updating it */ + if (likely(!reader || rb_page_write(reader) <= BUF_PAGE_SIZE)) + break; + + udelay(1); + + /* Get the latest version of the reader write value */ + smp_rmb(); + } + + /* The writer is not moving forward? Something is wrong */ + if (RB_WARN_ON(cpu_buffer, nr_loops == USECS_WAIT)) + reader = NULL; + + /* + * Make sure we see any padding after the write update + * (see rb_reset_tail()) + */ + smp_rmb(); + + return reader; }
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Yongqiang Liu