From: syzbot <syzbot+cb43e758a4dc84dd467f@syzkaller.appspotmail.com>
To: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
mchehab@kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [media?] KASAN: vmalloc-out-of-bounds Write in tpg_fill_plane_buffer (5)
Date: Mon, 17 Aug 2026 04:02:21 -0700 [thread overview]
Message-ID: <6a82ea3d.10853dc7.22f513.0024.GAE@google.com> (raw)
In-Reply-To: <6a63c6bd.a2ea2cc8.fbad6.0008.GAE@google.com>
syzbot has found a reproducer for the following issue on:
HEAD commit: 8d3ae59288f1 Linux 7.2
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14f80679580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d67342c314f228d
dashboard link: https://syzkaller.appspot.com/bug?extid=cb43e758a4dc84dd467f
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14b9d949580000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cb43e758a4dc84dd467f@syzkaller.appspotmail.com
BUG: KASAN: vmalloc-out-of-bounds in tpg_fill_plane_pattern drivers/media/common/v4l2-tpg/v4l2-tpg-core.c:2617 [inline]
BUG: KASAN: vmalloc-out-of-bounds in tpg_fill_plane_buffer+0x2063/0x4160 drivers/media/common/v4l2-tpg/v4l2-tpg-core.c:2705
Write of size 720 at addr ffffc900038f9d50 by task vivid-000-vid-c/6017
CPU: 0 UID: 0 PID: 6017 Comm: vivid-000-vid-c 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:
<TASK>
__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
check_region_inline mm/kasan/generic.c:186 [inline]
kasan_check_range+0x10f/0x1e0 mm/kasan/generic.c:200
__asan_memcpy+0x3c/0x60 mm/kasan/shadow.c:106
tpg_fill_plane_pattern drivers/media/common/v4l2-tpg/v4l2-tpg-core.c:2617 [inline]
tpg_fill_plane_buffer+0x2063/0x4160 drivers/media/common/v4l2-tpg/v4l2-tpg-core.c:2705
vivid_fillbuff+0x963/0x3ff0 drivers/media/test-drivers/vivid/vivid-kthread-cap.c:470
vivid_thread_vid_cap_tick+0x81b/0x1470 drivers/media/test-drivers/vivid/vivid-kthread-cap.c:629
vivid_thread_vid_cap+0x454/0xd70 drivers/media/test-drivers/vivid/vivid-kthread-cap.c:767
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
The buggy address belongs to a vmalloc virtual mapping
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802a460000 pfn:0x2a460
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: ffff88802a460000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 6016, tgid 6016 (syz-executor373), ts 77775340251, free_ts 77775265836
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304
__alloc_pages_noprof mm/page_alloc.c:5338 [inline]
alloc_pages_bulk_noprof+0x5de/0x13c0 mm/page_alloc.c:5230
alloc_pages_bulk_mempolicy_noprof+0x255/0x1270 mm/mempolicy.c:2798
vm_area_alloc_pages mm/vmalloc.c:3736 [inline]
__vmalloc_area_node mm/vmalloc.c:3914 [inline]
__vmalloc_node_range_noprof+0x69d/0x1630 mm/vmalloc.c:4104
vmalloc_user_noprof+0x9e/0xe0 mm/vmalloc.c:4259
vb2_vmalloc_alloc+0x135/0x410 drivers/media/common/videobuf2/videobuf2-vmalloc.c:47
__vb2_buf_mem_alloc drivers/media/common/videobuf2/videobuf2-core.c:242 [inline]
__vb2_queue_alloc+0x8d5/0x1160 drivers/media/common/videobuf2/videobuf2-core.c:523
vb2_core_reqbufs+0x899/0xf30 drivers/media/common/videobuf2/videobuf2-core.c:958
vb2_ioctl_reqbufs+0x291/0x450 drivers/media/common/videobuf2/videobuf2-v4l2.c:1036
vidioc_reqbufs+0x86/0x100 drivers/media/test-drivers/vivid/vivid-core.c:709
v4l_reqbufs+0x175/0x1d0 drivers/media/v4l2-core/v4l2-ioctl.c:2171
__video_do_ioctl+0xb2a/0xdf0 drivers/media/v4l2-core/v4l2-ioctl.c:3133
video_usercopy+0x47a/0x1730 drivers/media/v4l2-core/v4l2-ioctl.c:3475
v4l2_ioctl+0x1bd/0x250 drivers/media/v4l2-core/v4l2-dev.c:366
page last free pid 6016 tgid 6016 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950
__kasan_populate_vmalloc_do mm/kasan/shadow.c:393 [inline]
__kasan_populate_vmalloc+0x1ea/0x210 mm/kasan/shadow.c:424
kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
alloc_vmap_area+0x95d/0x2bb0 mm/vmalloc.c:2145
__get_vm_area_node+0x1ca/0x330 mm/vmalloc.c:3248
__vmalloc_node_range_noprof+0x228/0x1630 mm/vmalloc.c:4064
vmalloc_user_noprof+0x9e/0xe0 mm/vmalloc.c:4259
vb2_vmalloc_alloc+0x135/0x410 drivers/media/common/videobuf2/videobuf2-vmalloc.c:47
__vb2_buf_mem_alloc drivers/media/common/videobuf2/videobuf2-core.c:242 [inline]
__vb2_queue_alloc+0x8d5/0x1160 drivers/media/common/videobuf2/videobuf2-core.c:523
vb2_core_reqbufs+0x899/0xf30 drivers/media/common/videobuf2/videobuf2-core.c:958
vb2_ioctl_reqbufs+0x291/0x450 drivers/media/common/videobuf2/videobuf2-v4l2.c:1036
vidioc_reqbufs+0x86/0x100 drivers/media/test-drivers/vivid/vivid-core.c:709
v4l_reqbufs+0x175/0x1d0 drivers/media/v4l2-core/v4l2-ioctl.c:2171
__video_do_ioctl+0xb2a/0xdf0 drivers/media/v4l2-core/v4l2-ioctl.c:3133
video_usercopy+0x47a/0x1730 drivers/media/v4l2-core/v4l2-ioctl.c:3475
v4l2_ioctl+0x1bd/0x250 drivers/media/v4l2-core/v4l2-dev.c:366
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
Memory state around the buggy address:
ffffc900038f9f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc900038f9f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc900038fa000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
^
ffffc900038fa080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
ffffc900038fa100: 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.
prev parent reply other threads:[~2026-08-17 11:02 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-24 20:10 [syzbot] [media?] KASAN: vmalloc-out-of-bounds Write in tpg_fill_plane_buffer (5) syzbot
2026-08-17 11:02 ` syzbot [this message]
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