From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zenghui Yu Date: Wed, 24 Jul 2019 03:33:43 +0000 Subject: Re: [RFC PATCH] fbcon: fix ypos over boundary issue Message-Id: List-Id: References: <1562901216-9916-1-git-send-email-yuzenghui@huawei.com> <21374295-251c-e101-eaac-b86fffdb93ec@samsung.com> In-Reply-To: <21374295-251c-e101-eaac-b86fffdb93ec@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Bartlomiej Zolnierkiewicz Cc: dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, daniel.vetter@ffwll.ch, maarten.lankhorst@linux.intel.com, sam@ravnborg.org, linux-kernel@vger.kernel.org, wanghaibin.wang@huawei.com, zhang.zhanghailiang@huawei.com, yezengruan@huawei.com, Feng Tiantian Hi Bartlomiej, On 2019/7/23 23:59, Bartlomiej Zolnierkiewicz wrote: > > On 7/12/19 5:13 AM, Zenghui Yu wrote: >> From: Feng Tiantian >> >> While using "top" on a CentOS guest's VNC-client, then continuously press >> "Shift+PgUp", the guest kernel will get panic! Backtrace is attached below. >> We tested it on 5.2.0, and the issue remains. >> >> [ 66.946362] Unable to handle kernel paging request at virtual address ffff00000e240840 >> [ 66.946363] Mem abort info: >> [ 66.946364] Exception class = DABT (current EL), IL = 32 bits >> [ 66.946365] SET = 0, FnV = 0 >> [ 66.946366] EA = 0, S1PTW = 0 >> [ 66.946367] Data abort info: >> [ 66.946368] ISV = 0, ISS = 0x00000047 >> [ 66.946368] CM = 0, WnR = 1 >> [ 66.946370] swapper pgtable: 64k pages, 48-bit VAs, pgd = ffff000009660000 >> [ 66.946372] [ffff00000e240840] *pgd0000023ffe0003, *pud0000023ffe0003, *pmd0000023ffd0003, *pte00000000000000 >> [ 66.946378] Internal error: Oops: 96000047 [#1] SMP >> [ 66.946379] Modules linked in: vfat fat crc32_ce ghash_ce sg sha2_ce sha256_arm64 virtio_balloon virtio_net sha1_ce ip_tables ext4 mbcache jbd2 virtio_gpu drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm i2c_core virtio_scsi virtio_pci virtio_mmio virtio_ring virtio >> [ 66.946403] CPU: 0 PID: 1035 Comm: top Not tainted 4.14.0-49.el7a.aarch64 #1 >> [ 66.946404] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 >> [ 66.946405] task: ffff8001c18fdc00 task.stack: ffff00000d4e0000 >> [ 66.946409] PC is at sys_imageblit+0x40c/0x10000 [sysimgblt] >> [ 66.946431] LR is at drm_fb_helper_sys_imageblit+0x28/0x4c [drm_kms_helper] >> [ 66.946433] pc : [] lr : [] pstate: 00000005 >> [ 66.946433] sp : ffff00000d4ef7f0 >> [ 66.946434] x29: ffff00000d4ef7f0 x28: 00000000000001ff >> [ 66.946436] x27: ffff8001c1c88100 x26: 0000000000000001 >> [ 66.946438] x25: 00000000000001f0 x24: 0000000000000018 >> [ 66.946440] x23: 0000000000000000 x22: ffff00000d4ef978 >> [ 66.946442] x21: ffff00000e240840 x20: 0000000000000000 >> [ 66.946444] x19: ffff8001c98c9000 x18: 0000fffff9d56670 >> [ 66.946445] x17: 0000000000000000 x16: 0000000000000000 >> [ 66.946447] x15: 0000000000000008 x14: 1b20202020202020 >> [ 66.946449] x13: 00000000000001f0 x12: 000000000000003e >> [ 66.946450] x11: 000000000000000f x10: ffff8001c8400000 >> [ 66.946452] x9 : 0000000000aaaaaa x8 : 0000000000000001 >> [ 66.946454] x7 : ffff0000020b0090 x6 : 0000000000000001 >> [ 66.946456] x5 : 0000000000000000 x4 : 0000000000000000 >> [ 66.946457] x3 : ffff8001c8400000 x2 : ffff00000e240840 >> [ 66.946459] x1 : 00000000000001ef x0 : 0000000000000007 >> [ 66.946461] Process top (pid: 1035, stack limit = 0xffff00000d4e0000) >> [ 66.946462] Call trace: >> [ 66.946464] Exception stack(0xffff00000d4ef6b0 to 0xffff00000d4ef7f0) >> [ 66.946465] f6a0: 0000000000000007 00000000000001ef >> [ 66.946467] f6c0: ffff00000e240840 ffff8001c8400000 0000000000000000 0000000000000000 >> [ 66.946468] f6e0: 0000000000000001 ffff0000020b0090 0000000000000001 0000000000aaaaaa >> [ 66.946470] f700: ffff8001c8400000 000000000000000f 000000000000003e 00000000000001f0 >> [ 66.946471] f720: 1b20202020202020 0000000000000008 0000000000000000 0000000000000000 >> [ 66.946472] f740: 0000fffff9d56670 ffff8001c98c9000 0000000000000000 ffff00000e240840 >> [ 66.946474] f760: ffff00000d4ef978 0000000000000000 0000000000000018 00000000000001f0 >> [ 66.946475] f780: 0000000000000001 ffff8001c1c88100 00000000000001ff ffff00000d4ef7f0 >> [ 66.946476] f7a0: ffff000002202e74 ffff00000d4ef7f0 ffff0000020a040c 0000000000000005 >> [ 66.946478] f7c0: ffff00000d4ef7e0 ffff0000080ea614 0001000000000000 ffff000008152f08 >> [ 66.946479] f7e0: ffff00000d4ef7f0 ffff0000020a040c >> [ 66.946481] [] sys_imageblit+0x40c/0x10000 [sysimgblt] >> [ 66.946501] [] drm_fb_helper_sys_imageblit+0x28/0x4c [drm_kms_helper] >> [ 66.946510] [] virtio_gpu_3d_imageblit+0x2c/0x78 [virtio_gpu] >> [ 66.946515] [] bit_putcs+0x288/0x49c >> [ 66.946517] [] fbcon_putcs+0x114/0x148 >> [ 66.946519] [] do_update_region+0x118/0x19c >> [ 66.946521] [] do_con_trol+0x114c/0x1314 >> [ 66.946523] [] do_con_write.part.22+0x1d8/0x890 >> [ 66.946525] [] con_write+0x84/0x8c >> [ 66.946527] [] n_tty_write+0x19c/0x408 >> [ 66.946529] [] tty_write+0x150/0x270 >> [ 66.946532] [] __vfs_write+0x58/0x180 >> [ 66.946534] [] vfs_write+0xa8/0x1a0 >> [ 66.946536] [] SyS_write+0x60/0xc0 >> [ 66.946537] Exception stack(0xffff00000d4efec0 to 0xffff00000d4f0000) >> [ 66.946539] fec0: 0000000000000001 0000000000457958 0000000000000800 0000000000000000 >> [ 66.946540] fee0: 00000000fbad2885 0000000000000bd0 0000ffff8556add4 0000000000000000 >> [ 66.946541] ff00: 0000000000000040 0000000000000000 0000000000434a88 0000000000000012 >> [ 66.946543] ff20: 0000000100000000 0000fffff9d564f0 0000fffff9d564a0 0000000000000008 >> [ 66.946544] ff40: 0000000000000000 0000ffff85593b1c 0000fffff9d56670 0000000000000800 >> [ 66.946546] ff60: 0000000000457958 0000ffff856a1158 0000000000000800 0000ffff85720000 >> [ 66.946547] ff80: 0000000000000000 0000ffff856f604c 0000000000000000 0000000000436000 >> [ 66.946548] ffa0: 000000001c90a160 0000fffff9d56f20 0000ffff855965f4 0000fffff9d56f20 >> [ 66.946549] ffc0: 0000ffff855f12c8 0000000020000000 0000000000000001 0000000000000040 >> [ 66.946551] ffe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 66.946554] [] __sys_trace_return+0x0/0x4 >> [ 66.946556] Code: 0a080084 b86478e4 0a040124 4a050084 (b9000044) >> [ 66.946561] ---[ end trace 32d49c68b19c4796 ]--- >> [ 66.946562] Kernel panic - not syncing: Fatal exception >> [ 66.946564] SMP: stopping secondary CPUs >> [ 66.946596] Kernel Offset: disabled >> [ 66.946598] CPU features: 0x1802008 >> [ 66.946598] Memory Limit: none >> [ 67.092353] ---[ end Kernel panic - not syncing: Fatal exception >> >> >From our non-expert analysis, fbcon ypos will sometimes over boundary and >> then fbcon_putcs() access invalid VGA framebuffer address. We modify the >> real_y() to make sure fbcon ypos is always less than rows. >> >> Reported-by: Zengruan Ye >> Signed-off-by: Feng Tiantian >> Signed-off-by: Zenghui Yu >> --- >> >> Hi Bartlomiej, > > Hi Zenghui, > >> Zengruan had reported this issue [1] but received no reply. Does it make > > Sorry about that (at that time it seemed like a workaround for DRM issue > so I have not followed it further). > >> sense to fix this issue? Could you please take a look into this patch? > > It looks fine to me. I'll queue it for v5.4 on Friday (if there are > no issues raised by reviewers by then). Thanks for your reviewing! >> >> [1] https://lkml.org/lkml/2018/11/27/639 >> >> drivers/video/fbdev/core/fbcon.h | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/video/fbdev/core/fbcon.h b/drivers/video/fbdev/core/fbcon.h >> index 20dea85..b1aa00e 100644 >> --- a/drivers/video/fbdev/core/fbcon.h >> +++ b/drivers/video/fbdev/core/fbcon.h >> @@ -230,7 +230,10 @@ static inline int real_y(struct fbcon_display *p, int ypos) >> int rows = p->vrows; >> >> ypos += p->yscroll; >> - return ypos < rows ? ypos : ypos - rows; >> + if (rows = 0) >> + return ypos; >> + else >> + return ypos < rows ? ypos : ypos % rows; >> } This diff might equal to: return rows ? ypos % rows : ypos; If you're also happy with this simplification, could you please help to update this patch while applying? (Or we can send a v2. Please let us know which way do you prefer.) Thanks, zenghui