[syzbot] [fbdev?] KASAN: vmalloc-out-of-bounds Write in imageblit (4)

[syzbot] [fbdev?] KASAN: vmalloc-out-of-bounds Write in imageblit (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    670c12ce09a8 Merge tag 'for-6.11/dm-fixes' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11d41cdd980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7229118d88b4a71b
dashboard link: https://syzkaller.appspot.com/bug?extid=c4b7aa0513823e2ea880
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-670c12ce.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fdc54e331300/vmlinux-670c12ce.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e69f58032670/bzImage-670c12ce.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c4b7aa0513823e2ea880@syzkaller.appspotmail.com

FAULT_INJECTION: forcing a failure.
name fail_page_alloc, interval 1, probability 0, space 0, times 1
CPU: 0 UID: 0 PID: 5106 Comm: syz.0.0 Not tainted 6.11.0-rc3-syzkaller-00221-g670c12ce09a8 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail_ex+0x3b0/0x4e0 lib/fault-inject.c:153
 prepare_alloc_pages+0x1da/0x5d0 mm/page_alloc.c:4473
 __alloc_pages_noprof+0x166/0x6c0 mm/page_alloc.c:4689
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 ___kmalloc_large_node+0x8b/0x1d0 mm/slub.c:4103
 __kmalloc_large_node_noprof+0x1a/0x80 mm/slub.c:4130
 __do_kmalloc_node mm/slub.c:4146 [inline]
 __kmalloc_noprof+0x2ae/0x400 mm/slub.c:4170
 kmalloc_noprof include/linux/slab.h:685 [inline]
 kzalloc_noprof include/linux/slab.h:807 [inline]
 vc_do_resize+0x31b/0x17f0 drivers/tty/vt/vt.c:1174
 vc_resize include/linux/vt_kern.h:49 [inline]
 fbcon_set_disp+0xac9/0x11d0 drivers/video/fbdev/core/fbcon.c:1389
 con2fb_init_display drivers/video/fbdev/core/fbcon.c:794 [inline]
 set_con2fb_map+0xa6c/0x10a0 drivers/video/fbdev/core/fbcon.c:865
 fbcon_set_con2fb_map_ioctl+0x207/0x320 drivers/video/fbdev/core/fbcon.c:3092
 do_fb_ioctl+0x38f/0x7b0 drivers/video/fbdev/core/fb_chrdev.c:138
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f76311799b9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7631f9d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f7631315f80 RCX: 00007f76311799b9
RDX: 00000000200000c0 RSI: 0000000000004610 RDI: 0000000000000003
RBP: 00007f7631f9d090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 0000000000000000 R14: 00007f7631315f80 R15: 00007ffcf9b0e3e8
 </TASK>
==================================================================
BUG: KASAN: vmalloc-out-of-bounds in fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline]
BUG: KASAN: vmalloc-out-of-bounds in sys_imageblit+0x1ec6/0x2b00 drivers/video/fbdev/core/sysimgblt.c:326
Write of size 4 at addr ffffc90001c19000 by task syz.0.0/5106

CPU: 0 UID: 0 PID: 5106 Comm: syz.0.0 Not tainted 6.11.0-rc3-syzkaller-00221-g670c12ce09a8 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline]
 sys_imageblit+0x1ec6/0x2b00 drivers/video/fbdev/core/sysimgblt.c:326
 drm_fbdev_shmem_defio_imageblit+0x2e/0x100 drivers/gpu/drm/drm_fbdev_shmem.c:39
 bit_putcs+0x18ba/0x1db0
 fbcon_putcs+0x255/0x390 drivers/video/fbdev/core/fbcon.c:1288
 do_update_region+0x396/0x450 drivers/tty/vt/vt.c:619
 redraw_screen+0x902/0xe90 drivers/tty/vt/vt.c:971
 con2fb_init_display drivers/video/fbdev/core/fbcon.c:794 [inline]
 set_con2fb_map+0xa6c/0x10a0 drivers/video/fbdev/core/fbcon.c:865
 fbcon_set_con2fb_map_ioctl+0x207/0x320 drivers/video/fbdev/core/fbcon.c:3092
 do_fb_ioctl+0x38f/0x7b0 drivers/video/fbdev/core/fb_chrdev.c:138
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f76311799b9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7631f9d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f7631315f80 RCX: 00007f76311799b9
RDX: 00000000200000c0 RSI: 0000000000004610 RDI: 0000000000000003
RBP: 00007f7631f9d090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 0000000000000000 R14: 00007f7631315f80 R15: 00007ffcf9b0e3e8
 </TASK>

The buggy address belongs to the virtual mapping at
 [ffffc90001919000, ffffc90001c1a000) created by:
 drm_gem_shmem_vmap+0x3ac/0x630 drivers/gpu/drm/drm_gem_shmem_helper.c:343

Memory state around the buggy address:
 ffffc90001c18f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90001c18f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90001c19000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                   ^
 ffffc90001c19080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90001c19100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================


---
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#syz undup

Re: [syzbot] [fbdev?] KASAN: vmalloc-out-of-bounds Write in imageblit (4)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    c7fb1692dc01 Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11742d63980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=660f6eb11f9c7dc5
dashboard link: https://syzkaller.appspot.com/bug?extid=c4b7aa0513823e2ea880
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11703653980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=154565b7980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-c7fb1692.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/246da487db6f/vmlinux-c7fb1692.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f0ea1e4dac0f/bzImage-c7fb1692.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c4b7aa0513823e2ea880@syzkaller.appspotmail.com

R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000001
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
 </TASK>
==================================================================
BUG: KASAN: vmalloc-out-of-bounds in fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline]
BUG: KASAN: vmalloc-out-of-bounds in sys_imageblit+0x1ec6/0x2b00 drivers/video/fbdev/core/sysimgblt.c:326
Write of size 4 at addr ffffc90001c41000 by task syz-executor161/5103

CPU: 0 UID: 0 PID: 5103 Comm: syz-executor161 Not tainted 6.11.0-rc6-syzkaller-00048-gc7fb1692dc01 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline]
 sys_imageblit+0x1ec6/0x2b00 drivers/video/fbdev/core/sysimgblt.c:326
 drm_fbdev_shmem_defio_imageblit+0x2e/0x100 drivers/gpu/drm/drm_fbdev_shmem.c:39
 bit_putcs+0x18ba/0x1db0
 fbcon_putcs+0x255/0x390 drivers/video/fbdev/core/fbcon.c:1288
 do_update_region+0x396/0x450 drivers/tty/vt/vt.c:619
 redraw_screen+0x902/0xe90 drivers/tty/vt/vt.c:971
 con2fb_init_display drivers/video/fbdev/core/fbcon.c:794 [inline]
 set_con2fb_map+0xa6c/0x10a0 drivers/video/fbdev/core/fbcon.c:865
 fbcon_set_con2fb_map_ioctl+0x207/0x320 drivers/video/fbdev/core/fbcon.c:3092
 do_fb_ioctl+0x38f/0x7b0 drivers/video/fbdev/core/fb_chrdev.c:138
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7feb9b353729
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 a1 1a 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffde9b9f968 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffde9b9f980 RCX: 00007feb9b353729
RDX: 00000000200000c0 RSI: 0000000000004610 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffde9b9f707 R09: 00000000000000a0
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000001
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
 </TASK>

The buggy address belongs to the virtual mapping at
 [ffffc90001941000, ffffc90001c42000) created by:
 drm_gem_shmem_vmap+0x3ac/0x630 drivers/gpu/drm/drm_gem_shmem_helper.c:343

Memory state around the buggy address:
 ffffc90001c40f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90001c40f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90001c41000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                   ^
 ffffc90001c41080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90001c41100: 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.

Forwarded: KASAN: vmalloc-out-of-bounds in fast_imageblit

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: KASAN: vmalloc-out-of-bounds in fast_imageblit
Author: sravankumarlpu@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
 c7fb1692dc0139f95bd4131d3d5fa5eba2ba569e

Re: [syzbot] [fbdev?] KASAN: vmalloc-out-of-bounds Write in imageblit (4)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+c4b7aa0513823e2ea880@syzkaller.appspotmail.com
Tested-by: syzbot+c4b7aa0513823e2ea880@syzkaller.appspotmail.com

Tested on:

commit:         c7fb1692 Merge tag 'for-linus' of git://git.kernel.org..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=134ee9bc580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d573220e49f07420
dashboard link: https://syzkaller.appspot.com/bug?extid=c4b7aa0513823e2ea880
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=14e6e9bc580000

Note: testing is done by a robot and is best-effort only.