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SubjectKASAN: null-ptr-deref Read in uncore_pmu_event_add
From
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@syzkaller.appspotmail.com

==================================================================
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@googlegroups.com.

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

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