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<6ae995c6.24f6a368.35686f.0de8.GAE@google.com> Subject: Re: [syzbot] [fbdev?] KASAN: vmalloc-out-of-bounds Write in fillrect From: syzbot To: deller@gmx.de, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, osama.abdelkader@gmail.com, simona@ffwll.ch, soci@c64.rulez.org, syzkaller-bugs@googlegroups.com, tzimmermann@suse.de Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 6628e7d4c6b2 Linux 7.4-rc1 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=14484581580000 kernel config: https://syzkaller.appspot.com/x/.config?x=1d2c97eac7d33533 dashboard link: https://syzkaller.appspot.com/bug?extid=7a63ce155648954e749b compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=126c692d580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=140f1d59580000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-6628e7d4.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/2f9e962fc6ac/vmlinux-6628e7d4.xz kernel image: https://storage.googleapis.com/syzbot-assets/192b99738db6/bzImage-6628e7d4.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+7a63ce155648954e749b@syzkaller.appspotmail.com ================================================================== BUG: KASAN: vmalloc-out-of-bounds in fb_write_offset drivers/video/fbdev/core/sysmem.h:30 [inline] BUG: KASAN: vmalloc-out-of-bounds in bitfill drivers/video/fbdev/core/fb_fillrect.h:133 [inline] BUG: KASAN: vmalloc-out-of-bounds in fb_fillrect_static drivers/video/fbdev/core/fb_fillrect.h:219 [inline] BUG: KASAN: vmalloc-out-of-bounds in fb_fillrect drivers/video/fbdev/core/fb_fillrect.h:278 [inline] BUG: KASAN: vmalloc-out-of-bounds in sys_fillrect+0x174a/0x1910 drivers/video/fbdev/core/sysfillrect.c:24 Write of size 8 at addr ffffc900056fd000 by task syz.0.17/5992 CPU: 3 UID: 0 PID: 5992 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x13d/0x4b0 mm/kasan/report.c:482 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595 fb_write_offset drivers/video/fbdev/core/sysmem.h:30 [inline] bitfill drivers/video/fbdev/core/fb_fillrect.h:133 [inline] fb_fillrect_static drivers/video/fbdev/core/fb_fillrect.h:219 [inline] fb_fillrect drivers/video/fbdev/core/fb_fillrect.h:278 [inline] sys_fillrect+0x174a/0x1910 drivers/video/fbdev/core/sysfillrect.c:24 drm_fbdev_shmem_defio_fillrect+0x22/0x140 drivers/gpu/drm/drm_fbdev_shmem.c:39 bit_clear+0x17d/0x220 drivers/video/fbdev/core/bitblit.c:73 __fbcon_clear+0x633/0x760 drivers/video/fbdev/core/fbcon.c:1358 fbcon_scroll+0x48b/0x650 drivers/video/fbdev/core/fbcon.c:1910 con_scroll+0x464/0x690 drivers/tty/vt/vt.c:730 csi_M drivers/tty/vt/vt.c:2307 [inline] csi_ECMA.constprop.0+0x1238/0x3b60 drivers/tty/vt/vt.c:2730 do_con_trol drivers/tty/vt/vt.c:2945 [inline] do_con_write+0x366b/0x4ae0 drivers/tty/vt/vt.c:3442 con_write+0x23/0xb0 drivers/tty/vt/vt.c:3778 process_output_block drivers/tty/n_tty.c:557 [inline] n_tty_write+0x440/0x1200 drivers/tty/n_tty.c:2366 iterate_tty_write drivers/tty/tty_io.c:1008 [inline] file_tty_write.isra.0+0x4ca/0x8f0 drivers/tty/tty_io.c:1056 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6af/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3a15b9fb19 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe1abca668 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f3a15e25fa0 RCX: 00007f3a15b9fb19 RDX: 0000000000001006 RSI: 0000200000000680 RDI: 0000000000000006 RBP: 00007f3a15c37b70 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f3a15e25fac R14: 00007f3a15e25fa0 R15: 00007f3a15e25fa0 The buggy address belongs to a vmalloc virtual mapping Memory state around the buggy address: ffffc900056fcf00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc900056fcf80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >ffffc900056fd000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffffc900056fd080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc900056fd100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ================================================================== --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.