[syzbot] [dri?] KMSAN: uninit-value in drm_mode_setcrtc

[syzbot] [dri?] KMSAN: uninit-value in drm_mode_setcrtc

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    2741f1b02117 string: use __builtin_memcpy() in strlcpy/str..
git tree:       https://github.com/google/kmsan.git master
console+strace: https://syzkaller.appspot.com/x/log.txt?x=17bb33d1280000
kernel config:  https://syzkaller.appspot.com/x/.config?x=753079601b2300f9
dashboard link: https://syzkaller.appspot.com/bug?extid=4fad2e57beb6397ab2fc
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16d669a5280000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14d8f095280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ebd05512d8d7/disk-2741f1b0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/aa555b09582c/vmlinux-2741f1b0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5ea0934e02cc/bzImage-2741f1b0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4fad2e57beb6397ab2fc@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in drm_mode_setcrtc+0x1ad3/0x24a0 drivers/gpu/drm/drm_crtc.c:896
 drm_mode_setcrtc+0x1ad3/0x24a0 drivers/gpu/drm/drm_crtc.c:896
 drm_ioctl_kernel+0x5ae/0x730 drivers/gpu/drm/drm_ioctl.c:788
 drm_ioctl+0xd12/0x1590 drivers/gpu/drm/drm_ioctl.c:891
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0x222/0x400 fs/ioctl.c:856
 __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Uninit was created at:
 slab_post_alloc_hook+0x12d/0xb60 mm/slab.h:716
 slab_alloc_node mm/slub.c:3451 [inline]
 __kmem_cache_alloc_node+0x4ff/0x8b0 mm/slub.c:3490
 __do_kmalloc_node mm/slab_common.c:965 [inline]
 __kmalloc+0x121/0x3c0 mm/slab_common.c:979
 kmalloc_array include/linux/slab.h:596 [inline]
 drm_mode_setcrtc+0x1dba/0x24a0 drivers/gpu/drm/drm_crtc.c:846
 drm_ioctl_kernel+0x5ae/0x730 drivers/gpu/drm/drm_ioctl.c:788
 drm_ioctl+0xd12/0x1590 drivers/gpu/drm/drm_ioctl.c:891
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0x222/0x400 fs/ioctl.c:856
 __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

CPU: 1 PID: 4955 Comm: syz-executor275 Not tainted 6.4.0-rc4-syzkaller-g2741f1b02117 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
=====================================================


---
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Re: [syzbot] [dri?] KMSAN: uninit-value in drm_mode_setcrtc

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+4fad2e57beb6397ab2fc@syzkaller.appspotmail.com

Tested on:

commit:         d1d7f15c DO-NOT-SUBMIT: kmsan: add the kmsan_exceed_ma..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=101d3fdaa80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=36e4a2f8150fbc62
dashboard link: https://syzkaller.appspot.com/bug?extid=4fad2e57beb6397ab2fc
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15430342a80000

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