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SubjectRe: KASAN: use-after-free Read in find_uprobe
From
syzbot has found a reproducer for the following issue on:

HEAD commit: 0e2c50f4 Add linux-next specific files for 20210204
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12665674d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=b5009c5bf1512a87
dashboard link: https://syzkaller.appspot.com/bug?extid=9b2492a161dae05a29f0
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=178163e8d00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1094915f500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9b2492a161dae05a29f0@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in uprobe_cmp kernel/events/uprobes.c:620 [inline]
BUG: KASAN: use-after-free in __uprobe_cmp_key kernel/events/uprobes.c:646 [inline]
BUG: KASAN: use-after-free in rb_find include/linux/rbtree.h:289 [inline]
BUG: KASAN: use-after-free in __find_uprobe kernel/events/uprobes.c:661 [inline]
BUG: KASAN: use-after-free in find_uprobe+0x12c/0x150 kernel/events/uprobes.c:678
Read of size 8 at addr ffff888017f05d68 by task syz-executor109/8411

CPU: 1 PID: 8411 Comm: syz-executor109 Not tainted 5.11.0-rc6-next-20210204-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x107/0x163 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
uprobe_cmp kernel/events/uprobes.c:620 [inline]
__uprobe_cmp_key kernel/events/uprobes.c:646 [inline]
rb_find include/linux/rbtree.h:289 [inline]
__find_uprobe kernel/events/uprobes.c:661 [inline]
find_uprobe+0x12c/0x150 kernel/events/uprobes.c:678
uprobe_unregister+0x1e/0x70 kernel/events/uprobes.c:1111
__probe_event_disable+0x11e/0x240 kernel/trace/trace_uprobe.c:1084
probe_event_disable+0x155/0x1c0 kernel/trace/trace_uprobe.c:1171
trace_uprobe_register+0x45a/0x880 kernel/trace/trace_uprobe.c:1459
perf_trace_event_unreg.isra.0+0xac/0x250 kernel/trace/trace_event_perf.c:162
perf_uprobe_destroy+0xbb/0x130 kernel/trace/trace_event_perf.c:349
_free_event+0x2ee/0x1380 kernel/events/core.c:4830
put_event kernel/events/core.c:4924 [inline]
perf_event_release_kernel+0xa24/0xe00 kernel/events/core.c:5039
perf_release+0x33/0x40 kernel/events/core.c:5049
__fput+0x283/0x920 fs/file_table.c:280
task_work_run+0xdd/0x190 kernel/task_work.c:140
exit_task_work include/linux/task_work.h:30 [inline]
do_exit+0xc5c/0x2ae0 kernel/exit.c:825
do_group_exit+0x125/0x310 kernel/exit.c:922
__do_sys_exit_group kernel/exit.c:933 [inline]
__se_sys_exit_group kernel/exit.c:931 [inline]
__x64_sys_exit_group+0x3a/0x50 kernel/exit.c:931
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x43daf9
Code: Unable to access opcode bytes at RIP 0x43dacf.
RSP: 002b:00007ffd1d03f8e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00000000004ae230 RCX: 000000000043daf9
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00000000004ae230
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001

Allocated by task 8411:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:403 [inline]
____kasan_kmalloc mm/kasan/common.c:434 [inline]
____kasan_kmalloc.constprop.0+0xa0/0xd0 mm/kasan/common.c:406
kmalloc include/linux/slab.h:556 [inline]
kzalloc include/linux/slab.h:686 [inline]
alloc_uprobe kernel/events/uprobes.c:731 [inline]
__uprobe_register+0x19c/0x850 kernel/events/uprobes.c:1167
trace_uprobe_enable kernel/trace/trace_uprobe.c:1060 [inline]
probe_event_enable+0x357/0xa00 kernel/trace/trace_uprobe.c:1129
trace_uprobe_register+0x443/0x880 kernel/trace/trace_uprobe.c:1456
perf_trace_event_reg kernel/trace/trace_event_perf.c:129 [inline]
perf_trace_event_init+0x549/0xa20 kernel/trace/trace_event_perf.c:204
perf_uprobe_init+0x16f/0x210 kernel/trace/trace_event_perf.c:336
perf_uprobe_event_init+0xff/0x1c0 kernel/events/core.c:9721
perf_try_init_event+0x12a/0x560 kernel/events/core.c:11038
perf_init_event kernel/events/core.c:11090 [inline]
perf_event_alloc.part.0+0xe3b/0x3960 kernel/events/core.c:11370
perf_event_alloc kernel/events/core.c:11749 [inline]
__do_sys_perf_event_open+0x647/0x2e60 kernel/events/core.c:11847
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 8411:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
____kasan_slab_free.part.0+0xe1/0x110 mm/kasan/common.c:364
kasan_slab_free include/linux/kasan.h:191 [inline]
slab_free_hook mm/slub.c:1562 [inline]
slab_free_freelist_hook+0x82/0x1d0 mm/slub.c:1600
slab_free mm/slub.c:3161 [inline]
kfree+0xe5/0x7b0 mm/slub.c:4202
put_uprobe kernel/events/uprobes.c:612 [inline]
put_uprobe+0x13b/0x190 kernel/events/uprobes.c:601
uprobe_apply+0xfc/0x130 kernel/events/uprobes.c:1231
uprobe_perf_open kernel/trace/trace_uprobe.c:1311 [inline]
trace_uprobe_register+0x5c9/0x880 kernel/trace/trace_uprobe.c:1463
perf_trace_event_open kernel/trace/trace_event_perf.c:186 [inline]
perf_trace_event_init kernel/trace/trace_event_perf.c:208 [inline]
perf_trace_event_init+0x17a/0xa20 kernel/trace/trace_event_perf.c:195
perf_uprobe_init+0x16f/0x210 kernel/trace/trace_event_perf.c:336
perf_uprobe_event_init+0xff/0x1c0 kernel/events/core.c:9721
perf_try_init_event+0x12a/0x560 kernel/events/core.c:11038
perf_init_event kernel/events/core.c:11090 [inline]
perf_event_alloc.part.0+0xe3b/0x3960 kernel/events/core.c:11370
perf_event_alloc kernel/events/core.c:11749 [inline]
__do_sys_perf_event_open+0x647/0x2e60 kernel/events/core.c:11847
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff888017f05c00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 360 bytes inside of
512-byte region [ffff888017f05c00, ffff888017f05e00)
The buggy address belongs to the page:
page:00000000b82340ef refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x17f04
head:00000000b82340ef order:1 compound_mapcount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010841c80
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888017f05c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888017f05c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888017f05d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888017f05d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888017f05e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

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