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KCSAN: data-race in vga_arb_write / vga_arb_write (3)

Status: moderation: reported on 2024/04/09 06:54
Subsystems: pci
[Documentation on labels]
Reported-by: syzbot+071f6b8cc10b40158fa6@syzkaller.appspotmail.com
First crash: 21d, last: 21d
▶ ▼ Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in vga_arb_write / vga_arb_write dri 1 824d 824d 0/26 auto-closed as invalid on 2022/03/02 16:50
upstream KCSAN: data-race in vga_arb_write / vga_arb_write (2) pci 1 103d 103d 0/26 auto-obsoleted due to no activity on 2024/02/22 14:54

Sample crash report:
==================================================================
BUG: KCSAN: data-race in vga_arb_write / vga_arb_write

read to 0xffff888117283a24 of 4 bytes by task 6857 on cpu 0:
 vga_arb_write+0xed4/0x1410 drivers/pci/vgaarb.c:1250
 vfs_write+0x28b/0x8e0 fs/read_write.c:588
 ksys_write+0xeb/0x1b0 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:652
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

read-write to 0xffff888117283a24 of 4 bytes by task 6856 on cpu 1:
 vga_arb_write+0x1200/0x1410 drivers/pci/vgaarb.c:1204
 vfs_write+0x28b/0x8e0 fs/read_write.c:588
 ksys_write+0xeb/0x1b0 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:652
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

value changed: 0x00000027 -> 0x0000001c

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 6856 Comm: syz-executor.2 Tainted: G        W          6.9.0-rc3-syzkaller-00011-g20cb38a7af88 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/04/09 06:53 upstream 20cb38a7af88 f3234354 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in vga_arb_write / vga_arb_write
* Struck through repros no longer work on HEAD.