KASAN: null-ptr-deref Read in uncore_pmu_event_add

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    ac935d22 Add linux-next specific files for 20200415
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17f5743fe00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bc498783097e9019
dashboard link: https://syzkaller.appspot.com/bug?extid=832ccf42c61e3c63654e
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10fa7d40100000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17bfa540100000

Bisection is inconclusive: the bug happens on the oldest tested release.

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=16b06540100000
final crash:    https://syzkaller.appspot.com/x/report.txt?x=15b06540100000
console output: https://syzkaller.appspot.com/x/log.txt?x=11b06540100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+832ccf42c61e3c63654e@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:56 [inline]
BUG: KASAN: null-ptr-deref in test_bit include/asm-generic/bitops/instrumented-non-atomic.h:110 [inline]
BUG: KASAN: null-ptr-deref in uncore_msr_perf_ctr arch/x86/events/intel/uncore.h:335 [inline]
BUG: KASAN: null-ptr-deref in uncore_perf_ctr arch/x86/events/intel/uncore.h:378 [inline]
BUG: KASAN: null-ptr-deref in uncore_assign_hw_event arch/x86/events/intel/uncore.c:230 [inline]
BUG: KASAN: null-ptr-deref in uncore_pmu_event_add+0xa25/0x16d0 arch/x86/events/intel/uncore.c:602
Read of size 8 at addr 0000000000000000 by task syz-executor764/7073

CPU: 0 PID: 7073 Comm: syz-executor764 Not tainted 5.7.0-rc1-next-20200415-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 __kasan_report.cold+0x5/0x4d mm/kasan/report.c:515
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 check_memory_region_inline mm/kasan/generic.c:187 [inline]
 check_memory_region+0x141/0x190 mm/kasan/generic.c:193
 instrument_atomic_read include/linux/instrumented.h:56 [inline]
 test_bit include/asm-generic/bitops/instrumented-non-atomic.h:110 [inline]
 uncore_msr_perf_ctr arch/x86/events/intel/uncore.h:335 [inline]
 uncore_perf_ctr arch/x86/events/intel/uncore.h:378 [inline]
 uncore_assign_hw_event arch/x86/events/intel/uncore.c:230 [inline]
 uncore_pmu_event_add+0xa25/0x16d0 arch/x86/events/intel/uncore.c:602
 </IRQ>
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 7073 Comm: syz-executor764 Tainted: G    B             5.7.0-rc1-next-20200415-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 end_report+0x4d/0x53 mm/kasan/report.c:103
 __kasan_report.cold+0xd/0x4d mm/kasan/report.c:518
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 check_memory_region_inline mm/kasan/generic.c:187 [inline]
 check_memory_region+0x141/0x190 mm/kasan/generic.c:193
 instrument_atomic_read include/linux/instrumented.h:56 [inline]
 test_bit include/asm-generic/bitops/instrumented-non-atomic.h:110 [inline]
 uncore_msr_perf_ctr arch/x86/events/intel/uncore.h:335 [inline]
 uncore_perf_ctr arch/x86/events/intel/uncore.h:378 [inline]
 uncore_assign_hw_event arch/x86/events/intel/uncore.c:230 [inline]
 uncore_pmu_event_add+0xa25/0x16d0 arch/x86/events/intel/uncore.c:602
 </IRQ>
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches